A new process for producing synthetic diamonds can be operated at a profitable level only if the average weight of the diamonds produced by the process is greater than 0. 5 karat. To evaluate the profitability of the process, a sample of six diamonds was generated using this new process, with recorded weights . 46, . 61, . 52, . 48, . 57, and . 54 karat. Do the six measurements present sufficient evidence to indicate that the average weight of the diamonds produced by the new process is in excess of 0. 5 karat? To answer this question conduct an appropriate test of hypothesis using the five step process outlined in our textbook and utilized in the solutions to the Chapter 8 review problems, which are posted in the Review Problem Sets Solutions folder in the Resources section of our classroom. To make a post to this week's Challenge Discussion Forum, click on the Testing a Hypothesis link, then click Post New Thread. In the title block of the dialog box that appears kindly insert your first and last name; compose your post in the message box; and then click Post Message.

Question 1 of 25

0. 0/ 1. 0 Points

For a boxplot, the vertical line inside the box indicates the location of the

A. median

B. mode

In C. mean

D. inter quartile range

Answer Key:

Part 2 of 9 - 2. 0/ 2. 0 Points

Question 2 of 25

1. 0/ 1. 0 Points

If events A and B are mutually exclusive, then the probability of both events occurring simultaneously is equal to

A. 0. 5

B. 1. 0

C. any value between 0. 5 and 1. 0

D. 0. 0

Answer Key:

Question 3 of 25

1. 0/ 1. 0 Points

If P(A) = P(A|B), then events A and B are said to be

A. complementary

B. mutually exclusive

C. exhaustive

D. independent

Answer Key:

Part 3 of 9 - 3. 0/ 3. 0 Points

Question 4 of 25

1. 0/ 1. 0 Points

Suppose that 50 identical batteries are being tested. After 8 hours of continuous use, assume that a given battery is still operating with a probability of 0. 70 and has failed with a probability of 0. 30.

What is the probability that greater than 40 batteries will last at least 8 hours?

A. 0. 0789

B. 0. 4538

C. 0. 9598

D. 0. 0402

Answer Key:

Question 5 of 25

1. 0/ 1. 0 Points

If a gambler rolls two dice and gets a sum of 10, he wins $10, and if he gets a sum of three, he wins $20. The cost to play the game is $5. What is the expectation of this game?

A. $3. 06

B. -$2. 78

C. -$3. 06

D. $2. 78

Answer Key:

Question 6 of 25

1. 0/ 1. 0 Points

There are two types of random variables, they are

A. real and unreal

B. exhaustive and mutually exclusive

C. complementary and cumulative

D. discrete and continuous

Answer Key:

Part 4 of 9 - 5. 0/ 6. 0 Points

Question 7 of 25

1. 0/ 1. 0 Points

The theorem that states that the sampling distribution of the sample mean is approximately normal when the sample size n is reasonably large is known as the:

A. simple random sample theorem

B. central tendency theorem

C. point estimate theorem

D. central limit theorem

Answer Key:

Question 8 of 25

1. 0/ 1. 0 Points

The normal distribution is:

A. a binomial distribution with only one parameter

B. a discrete distribution

C. a density function of a discrete random variable

D. the single most important distribution in statistics

Answer Key:

Question 9 of 25

1. 0/ 1. 0 Points

If Z is a standard normal random variable, then the value z for which P(-z < Z < z) equals 0. 8764 is

A. 1. 16

B. 0. 3764

C. 1. 54

D. 3. 08

Answer Key:

Question 10 of 25

1. 0/ 1. 0 Points

Given that Z is a standard normal random variable, P(-1. 0 < Z < 1. 5) is

A. 0. 9332

B. 0. 0919

C. 0. 7745

D. 0. 8413

Answer Key:

Question 11 of 25

0. 0/ 1. 0 Points

One reason for standardizing random variables is to measure variables with:

A. different means and standard deviations on a non-standard scale

B. dissimilar means and similar standard deviations in like terms

In C. similar means and standard deviations on two scales

D. different means and standard deviations on a single scale

Answer Key:

Question 12 of 25

1. 0/ 1. 0 Points

The standard deviation of a probability distribution is a:

A. measure of variability of the distribution

B. measure of central location

C. measure of skewness of the distribution

D. measure of relative likelihood

Answer Key:

Part 5 of 9 - 1. 0/ 1. 0 Points

Question 13 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A sample of 150 students at a State University was taken after the final business statistics exam to ask them whether they went partying the weekend before the final or spent the weekend studying, and whether they did well or poorly on the final. The following table contains the result.

Did Well on Exam Did Poorly on Exam

Studying for Exam 60 15

Went Partying 22 53

If the sample is a good representation of the population, what percentage of the students in the population should we expect to spend the weekend studying and do poorly on the final exam? Place your answer in the blank, rounded to 2 decimal places. Do not use a percentage sign (%). For example, 44. 44 would be a legitimate answer. 10. 00

Answer Key:

Part 6 of 9 - 2. 0/ 2. 0 Points

Question 14 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Find the mean of the distribution shown below.

X 0 1 2

P(X) 0. 24 0. 31 0. 45

Round your answer to two decimal place as necessary. For example, 4. 56 would be a legitimate entry.

Mean = 1. 21

Answer Key:

Feedback: Expected value = (0)(0. 24) + (1)(0. 31) + (2)(0. 45) = 1. 21

Question 15 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Find the mean of the following probability distribution.

X 1 2 3 4 5

P(X) 0. 20 0. 10 0. 35 0. 05 0. 30

Round your answer to two decimal place as necessary. For example, 4. 56 would be a legitimate entry.

Mean = 3. 15

Answer Key:

Part 7 of 9 - 2. 0/ 2. 0 Points

Question 16 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

At a certain college, there were 600 science majors, 200 engineering majors, and 500 business majors. If a student is selected at random, what is the probability that the student is an engineering major?

Place your answer, rounded to four decimal places, in the blank. 0. 1538 When entering your answer do not use any labels or symbols other than a decimal point. Simply provide the numerical value. For example, 0. 1234 would be a legitimate entry.

Answer Key: 0

Question 17 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A reading list for a course contains 20 articles. How many ways are there to choose three articles from this list? Place your answer in the blank. Do not use any decimal places or commas. For example, 45 would be a legitimate entry. 1140

Answer Key:

Part 8 of 9 - 5. 0/ 6. 0 Points

Question 18 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Suppose that the average weekly earnings for employees in general automotive repair shops is $450, and that the standard deviation for the weekly earnings for such employees is $50. A sample of 100 such employees is selected at random.

Find the probability that the mean of the sample is between $445 and $455. Place your answer, rounded to 4 decimal places, in the blank. For example, 0. 2345 would be a legitimate entry. 0. 6826

Answer Key: 0.

Question 19 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The mean weight of loads of coal placed in train cars by a loading machine is 43. 0 tons with a standard deviation of 8. 0 tons. Assuming that the weight of loads placed in the train cars by this loader are normally distributed, if a random sample of 9 loads is chosen for a weight check, find the probability that the mean weight of those loads is more than 40. 60 tons.

Place your answer, rounded to four decimal places, in the blank. 0. 8159 When entering your answer do not use any labels or symbols other than a decimal point. Simply provide the numerical value. For example, 0. 1234 would be a legitimate entry.

Answer Key: 0

Question 20 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Scores on a mathematics examination appear to follow a normal distribution with mean of 65 and standard deviation of 15. The instructor wishes to give a grade of “C” to students scoring between the 60th and 70th percentiles on the exam.

What score represents the 60th percentile score on the mathematics exam? Place your answer in the blank, rounded to a whole number. For example, 62 would be a legitimate entry. 69

Answer Key:

Question 21 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A Wendy’s fast-food restaurant sells hamburgers and chicken sandwiches. On a typical weekday, the demand for hamburgers is normally distributed with a mean of 450 and standard deviation of 80 and the demand for chicken sandwiches is normally distributed with a mean of 120 and standard deviation of 30.

How many hamburgers must the restaurant stock to be 99% sure of not running out on a given day? Place you answer, rounded to the nearest whole number in the blank. For example, 345 would be a legitimate entry. 637

Answer Key:

Question 22 of 25

0. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The manufacturer of a new compact car claims the miles per gallon (mpg) for the gasoline consumption is mound shaped and symmetric with a mean of 25. 9 mpg and a standard deviation of 9. 5 mpg. If 30 such cars are tested, what is the probability the average mpg achieved by these 30 cars will be greater than 28? Place your answer, rounded to 4 decimal places, in the blank. 0. 3520

Answer Key: 0.

Question 23 of 25

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A popular retail store knows that the purchase amounts by its customers is a random variable that follows a normal distribution with a mean of $30 and a standard deviation of $9.

What is the probability that a randomly selected customer will spend less than $15 at this store? Place your answer, rounded to 4 decimal places, in the blank. For example, 0. 3456 would be a legitimate entry. . 0478

Answer Key:

Part 9 of 9 - 1. 0/ 2. 0 Points

Question 24 of 25

1. 0/ 1. 0 Points

The sampling distribution of the mean will have the same mean as the original population from which the samples were drawn.

True

False

Answer Key: True

Question 25 of 25

0. 0/ 1. 0 Points

Using the standard normal curve, the Z- score representing the 5th percentile is 1. 645.

In

True

False

Answer Key:

Question 1 of 20

1. 0/ 1. 0 Points

The total frequency of the data whose ogive is shown below is approximately

A. 12

B. 18

C. 34

D. 90

Answer Key:

Question 2 of 20

1. 0/ 1. 0 Points

The length of the box in the boxplot portrays the

A. median

B. mean

C. interquartile range

D. range

Answer Key:

Question 3 of 20

1. 0/ 1. 0 Points

Which measure of central location is meaningful when the data are categorical?

A. The mean

B. The mode

C. The median

D. The range

Answer Key:

Question 4 of 20

1. 0/ 1. 0 Points

Data that arise from counts are called:

A. counted data

B. nominal data

C. discrete data

D. continuous data

Answer Key:

Question 5 of 20

1. 0/ 1. 0 Points

The median can also be described as:

A. the middle observation when the data values are arranged in ascending orde

B. the second quartile

C. the 50th percentile

D. all of the above

Answer Key:

Question 6 of 20

1. 0/ 1. 0 Points

A scatterplot allows one to see:

A. whether there is any relationship between two variables

B. what type of relationship there is between two variables

C. Both (a) and (b) are

D. Neither (a) nor (b) is

Answer Key:

Question 7 of 20

0. 0/ 1. 0 Points

Suppose that a histogram of a data set is approximately symmetric and "bell shaped". Approximately what percent of the observations are within one standard deviation of the mean?

A. 50%

B. 68%

C. 99. 7%

In D. 95%

Answer Key:

Question 8 of 20

1. 0/ 1. 0 Points

Researchers may gain insight into the characteristics of a population by examining a

A. replica

B. sample of the population

C. description of the population

D. mathematical model describing the population

Answer Key:

Question 9 of 20

1. 0/ 1. 0 Points

The difference between the first and third quartile is called the

A. interquartile range

B. interdependent range

C. mid range

D. unimodal range

Answer Key:

Question 10 of 20

1. 0/ 1. 0 Points

Boxplots are most useful for.

A. comparing the mean to the median

B. comparing two populations graphically

C. calculating the mean of the data

D. calculating the median of the data

Answer Key:

Question 11 of 20

0. 0/ 1. 0 Points

Find the z-score for each student and indicate which one has a better relative position. An Art Major earned a grade of 46 on an exam with f$ar{x}f$ = 50 and s = 5; A Theater Major earned a grade of 70 on an exam with f$ar{x}f$ = 75 and s = 7.

A. Both students have the same score.

B. The theater major has a higher relative position than the art major.

C. The higher score cannot be determined.

In D. The art major has a higher relative position than the theater major.

Answer Key:

Question 12 of 20

1. 0/ 1. 0 Points

What type of graph is the figure below?

A. ogive

B. Pareto chart

C. relative frequency histogram

D. pictograph

Answer Key:

Part 2 of 3 - 4. 0/ 6. 0 Points

Question 13 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The following data represent the number of children in a sample of 10 families from Chicago: 4, 2, 1, 1, 5, 3, 0, 1, 0, and 2.

Compute the mean number of children. Place your answer, rounded to two decimal places, in the blank. For example, 3. 45 would be a legitimate entry. 1. 90

Answer Key:

Question 14 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A student scored 84 points on a test where the mean score was 79 and the standard deviation was 4. Find the student's z score, rounded to 2 decimal places, and place it in the blank. 1. 25

Answer Key:

Question 15 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The following data represent the number of children in a sample of 10 families from Chicago: 4, 2, 1, 1, 5, 3, 0, 1, 0, and 2.

Compute the median number of children. Place your answer, rounded to two decimal places, in the blank. For example, 3. 45 would be a legitimate entry. 1. 50

Answer Key:

Question 16 of 20

1. 0/ 1. 0 Points

mployees spend on work-related activities in a typical week. Rather than reviewing the records of all the firm’s full-time employees, the management randomly selected a sample of size 51 from the available frame. The sample mean and sample standard deviations were 48. 5 and 7. 5 hours, respectively.

Construct a 90% confidence interval for the standard deviation of the number of hours this firm’s employees spend on work-related activities in a typical week.

Place your LOWER limit, in hours, rounded to 1 decimal place, in the first blank. For example, 6. 7 would be a legitimate entry. Correct46. 8

Place your UPPER limit, in hours, rounded to 1 decimal place, in the second blank. For example, 12. 3 would be a legitimate entry. Correct50. 2

Answer Key:

Question 3 of 20

0. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The manufacturer of a new compact car claims the miles per gallon (mpg) for the gasoline consumption is mound-shaped and symmetric with a mean of 25. 9 mpg and a standard deviation of 9. 5 mpg. If 30 such cars are tested, what is the probability the average mpg achieved by these 30 cars will be greater than 28?

Answer: Correct. 1037 Round your answer to 4 decimal places as necessary. For example, 0. 1357 would be a legitimate entry.

Answer Key:

Feedback: This is a sampling distribution problem with ? = 25. 9. ? = 9. 5, and sample size n = 30.

f[z=frac{28-25. 9}{9. 5/sqrt{30}} = 1. 210755f]

P(z > 1. 210755) = 1 – NORMSDIST(1. 210755) = 0. 1130

Or you can compute the probability without having to compute z first:

P(x-bar > 28) = 1 – NORMDIST(28, 25. 9, 9. 5/SQRT(30), TRUE) = 0. 1130

Question 4 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

You are told that a random sample of 150 people from Iowa has been given cholesterol tests, and 60 of these people had levels over the “safe” count of 200. Construct a 95% confidence interval for the population proportion of people in Iowa with cholesterol levels over 200. Place your LOWER limit, rounded to 3 decimal places, in the first blank Correct. 322 . For example, . 678 would be a legitimate entry. Place your UPPER limit, rounded to 3 decimal places, in the second blank Correct. 478 . For example, . 789 would be a legitimate entry.

Answer Key: .

Question 5 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Senior management of a consulting services firm is concerned about a growing decline in the firm’s weekly number of billable hours. The firm expects each professional employee to spend at least 40 hours per week on work. In an effort to understand this problem better, management would like to estimate the standard deviation of the number of hours their employees spend on work-related activities in a typical week. Rather than reviewing the records of all the firm’s full-time employees, the management randomly selected a sample of size 51 from the available frame. The sample mean and sample standard deviations were 48. 5 and 7. 5 hours, respectively.

Construct a 95% confidence interval for the standard deviation of the number of hours this firm’s employees spend on work-related activities in a typical week.

Place your LOWER limit, in hours, rounded to 1 decimal place, in the first blank. For example, 6. 7 would be a legitimate entry. Correct6. 3

Place your UPPER limit, in hours, rounded to 1 decimal place, in the second blank. For example, 12. 3 would be a legitimate entry. Correct9. 3

Answer Key:

Question 6 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A marketing research consultant hired by Coca-Cola is interested in determining the proportion of customers who favor Coke over other soft drinks. A random sample of 400 consumers was selected from the market under investigation and showed that 53% favored Coca-Cola over other brands.

Compute a 95% confidence interval for the true proportion of people who favor Coke. Place your LOWER limit, rounded to 3 decimal places, in the first blank Correct. 481 . For example, . 345 would be a legitimate entry. Place your UPPER limit in the second blank Correct. 579 . For example, . 456 would be a legitimate entry.

Answer Key:

Question 7 of 20

0. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The personnel department of a large corporation wants to estimate the family dental expenses of its employees to determine the feasibility of providing a dental insurance plan. A random sample of 12 employees reveals the following family dental expenses (in dollars): 115, 370, 250, 593, 540, 225, 177, 425, 318, 182, 275, and 228.

Construct a 90% confidence interval estimate for the standard deviation of family dental expenses for all employees of this corporation.

Place your LOWER limit, in dollars rounded to 1 decimal place, in the first blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 123. 4 would be a legitimate entry. Correct231. 5

Place your UPPER limit, in dollars rounded to 1 decimal place, in the second blank. Do not use a dollar sign, a comma, or any other stray mark. For example, 567. 8 would be a legitimate entry. Correct384. 9

Answer Key:

Part 2 of 3 - 10. 0/ 11. 0 Points

Question 8 of 20

1. 0/ 1. 0 Points

In constructing a confidence interval estimate for a population mean, when we replace f$sigma f$ with the sample standard deviation (s), we introduce a new source of variability and the sampling distribution we use is:

A. F- distribution

B. the normal distribution

C. chi-square distribution

Correct D. t -distribution

Answer Key:

Question 9 of 20

1. 0/ 1. 0 Points

A food snack manufacturer samples 15 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 10. 0 and the sample standard deviation is 0. 15, find the 95% confidence interval estimate for the true mean.

A. (9. 96, 10. 04)

B. (9. 68, 10. 32)

C. (9. 97, 10. 80)

Correct D. (9. 92, 10. 08)

Answer Key:

Question 10 of 20

1. 0/ 1. 0 Points

In a study of elephants a researcher wishes to determine the average weight of a certain subspecies of elephants. From previous studies, the standard deviation of the weights of elephants in this subspecies is known to be 1500 pounds. How many elephants does the researcher need to weigh so that he can be 80% confident that the average weight of elephants in his sample is within 350 pounds of the true average weight for this subspecies?

A. 50

B. 39

C. 166

Correct

Answer Key:

Question 11 of 20

0. 0/ 1. 0 Points

If you increase the confidence level, the confidence interval ____________.

A. stays the same

B. decreases

C. increases

Incorrect D. may increase or decrease, depending on the sample data

Answer Key:

Question 12 of 20

1. 0/ 1. 0 Points

The average gas mileage of a certain model car is 26 miles per gallon. If the gas mileages are normally distributed with a standard deviation of 1. 3, find the probability that a randomly selected car of this model has a gas mileage between 25. 8 and 26. 3 miles per gallon.

Correct A. 0. 15

B. 0. 85

C. 0. 70

D. 0. 30

Answer Key:

Question 13 of 20

1. 0/ 1. 0 Points

At a large department store, the average number of years of employment for a cashier is 5. 7 with a standard deviation of 1. 8 years. If the number of years of employment at this department store is normally distributed, what is the probability that a cashier selected at random has worked at the store for over 10 years?

A. 0. 4916

B. 0. 9916

Correct C. 0. 0084

D. 0. 0054

Answer Key:

Question 14 of 20

1. 0/ 1. 0 Points

In order to be accepted into a top university, applicants must score within the top 5% on the SAT exam. Given that SAT test scores are normally distributed with a mean of 1000 and a standard deviation of 200, what is the lowest possible score a student needs to qualify for acceptance into the university?

Correct A. 1330

B. 1400

C. 1250

D. 1100

Answer Key:

Question 15 of 20

1. 0/ 1. 0 Points

From a sample of 500 items, 30 were found to be defective. The point estimate of the population proportion defective will be:

A. 30

B. 0. 60

C. 16. 667

Correct D. . 06

Answer Key

Question 16 of 20

1. 0/ 1. 0 Points

The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and f$hat{p}f$ = 0. 20 is

A. 0. 4684

Correct B. 0. 2658

C. 0. 5316

D. 0. 7342

Answer Key

Question 17 of 20

1. 0/ 1. 0 Points

Which of the following will make a confidence interval narrower and more precise?

A. Larger sample size and higher confidence level

B. Smaller sample size and lower confidence level

Correct C. Larger sample size and lower confidence level

D. Smaller sample size and higher confidence level

Answer Key

Question 18 of 20

1. 0/ 1. 0 Points

The t- distribution for developing a confidence interval for a mean has _____ degrees of freedom.

A. n - 2

B. n + 1

Correct C. n - 1

D. n

Answer Key

Part 3 of 3 - 2. 0/ 2. 0 Points

Question 19 of 20

1. 0/ 1. 0 Points

The lower limit of the 95% confidence interval for the population proportion p, given that n = 300; and f$hat{p}f$ = 0. 10 is 0. 1339.

Correct

True

False

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Question 20 of 20

1. 0/ 1. 0 Points

The upper limit of the 90% confidence interval for the population proportion p, given that n = 100; and f$hat{p}f$ = 0. 20 is 0. 2341.

Correct

True

False

Answer Key

Question 1 of 20

1. 0/ 1. 0 Points

A severe storm has an average peak wave height of 16. 4 feet for waves hitting the shore. Suppose that a storm is in progress with a severe storm class rating. Let us say that we want to set up a statistical test to see if the wave action (i. e. , height) is dying down or getting worse. If you wanted to test the hypothesis that the waves are dying down, what would you use for the alternate hypothesis? Is the P-value area on the left, right, or on both sides of the mean?

Correct A. H1: \f$\mu \f$ is less than 16. 4 feet; the P-value area is on the left of the mean

B. H1: \f$\mu \f$ is greater than 16. 4 feet; the P-value area is on both sides of the mean

C. H1: \f$\mu \f$ is greater than 16. 4 feet; the P-value area is on the left of the mean

D. H1: \f$\mu \f$ is not equal to 16. 4 feet; the P-value area is on the right of the mean

Answer Key:

Question 2 of 20

1. 0/ 1. 0 Points

A lab technician is tested for her consistency by taking multiple measurements of cholesterol levels from the same blood sample. The target accuracy is a variance in measurements of 1. 2 or less. If the lab technician takes 16 measurements and the variance of the measurements in the sample is 2. 2, does this provide enough evidence to reject the claim that the lab technician’s accuracy is within the target accuracy?

State the null and alternative hypotheses.

A. H0: s2 ? 1. 2, H1: s2 = 1. 2

B. H0: s2 < 1. 2, H1: s2 ? 1. 2

C. H0: s2 ? 1. 2, H1: s2 ? 1. 2

Correct D. H0: s2 ? 1. 2, H1: s2 > 1. 2

Answer Key:

Question 3 of 20

0. 0/ 1. 0 Points

A null hypothesis can only be rejected at the 5% significance level if and only if:

Incorrect A. the null hypotheses includes sampling error

B. a 95% confidence interval includes the hypothesized value of the parameter

C. a 95% confidence interval does not include the hypothesized value of the parameter

D. the null hypothesis is biased

Answer Key:

Question 4 of 20

1. 0/ 1. 0 Points

The alternative hypothesis is also known as the:

A. optional hypothesis

Correct B. research hypothesis

C. null hypothesis

D. elective hypothesis

Answer Key:

Question 5 of 20

1. 0/ 1. 0 Points

The null and alternative hypotheses divide all possibilities into:

A. two sets that overlap

B. two sets that may or may not overlap

Correct C. two non-overlapping sets

D. as many sets as necessary to cover all possibilities

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Question 6 of 20

1. 0/ 1. 0 Points

A type I error occurs when the:

Correct A. null hypothesis is incorrectly rejected when it is true

B. sample mean differs from the population mean

C. null hypothesis is incorrectly accepted when it is false

D. test is biased

Answer Key:

Question 7 of 20

0. 0/ 1. 0 Points

A lab technician is tested for her consistency by taking multiple measurements of cholesterol levels from the same blood sample. The target accuracy is a variance in measurements of 1. 2 or less. If the lab technician takes 16 measurements and the variance of the measurements in the sample is 2. 2, does this provide enough evidence to reject the claim that the lab technician’s accuracy is within the target accuracy?

At the a = . 01 level of significance, what is your conclusion?

A.

Reject H0. At the \f$\alpha \f$ = . 01 level of significance, there is not enough evidence to support the claim that this technician’s true variance is larger than the target accuracy.

Incorrect B. Reject H0. At the \f$\alpha \f$ = . 01 level of significance, there is enough evidence to support the claim that this technician’s variance is larger than the target accuracy.

C. Do not reject H0. At the \f$\alpha \f$ = . 01 level of significance there is not sufficient evidence to suggest that this technician’s true variance is greater than the target accuracy.

D. Cannot determine

Answer Key:

Question 8 of 20

1. 0/ 1. 0 Points

Smaller p-values indicate more evidence in support of the:

Correct A. alternative hypothesis

B. quality of the researcher

C. null hypothesis

D. the reduction of variance

Answer Key:

Question 9 of 20

1. 0/ 1. 0 Points

In an article appearing in Today’s Health a writer states that the average number of calories in a serving of popcorn is 75. To determine if the average number of calories in a serving of popcorn is different from 75, a nutritionist selected a random sample of 20 servings of popcorn and computed the sample mean number of calories per serving to be 78 with a sample standard deviation of 7.

State the null and alternative hypotheses.

A. H0: \f$\mu \f$ \f$\leq \f$ 75, H1: \f$\mu \f$ > 75

Correct B. H0: \f$\mu \f$ = 75, H1: \f$\mu \f$ ? 75

C. H0: \f$\mu \f$ \f$\geq \f$ 75, H1: \f$\mu \f$ < 75

D. H0: \f$\mu \f$ = 75, H1: \f$\mu \f$ > 75

Answer Key:

Question 10 of 20

1. 0/ 1. 0 Points

The “Pizza Hot” manager commits a Type I error if he/she is

A. staying with old style when new style is better

B. staying with old style when new style is no better than old style

C. switching to new style when it is better than old style

Correct D. switching to new style when it is no better than old style

Answer Key:

Question 11 of 20

0. 0/ 1. 0 Points

You conduct a hypothesis test and you observe values for the sample mean and sample standard deviation when n = 25 that do not lead to the rejection of H0. You calculate a p-value of 0. 0667. What will happen to the p-value if you observe the same sample mean and standard deviation for a sample size larger than 25?

A. The p – value increases

B. The p – value decreases

Incorrect C. The p – value may increase or decrease

D. The p – value stays the same

Answer Key:

Part 2 of 3 - 3. 0/ 6. 0 Points

Question 12 of 20

0. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A survey determines that mint chocolate chip is the favorite ice cream flavor of 6% of consumers. An ice cream shop determines that of 240 customers, 18 customers stated their preference for mint chocolate chip.

Find the P-value that would be used to determine if the percentage of customers who prefer mint chocolate chip ice has increased at a 5% level of significance.

P-value: Correct. 3278 Round your answer to four decimal places as necessary.

Answer Key: 0. 1635|0. 1639

Feedback: This is a right-tail hypothesis test with a test statistic of z = 0. 978492.

Question 13 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The ABC battery company claims that their batteries last 100 hours, on average. You decide to conduct a test to see if the company's claim is true. You believe that the mean life may be different from the 100 hours the company claims. You decide to collect data on the average battery life (in hours) of a random sample of n = 20 batteries. Some of the information related to the hypothesis test is presented below.

Test of H0: f$mu f$ = 100 versus H1: f$mu

eq f$ 100

Sample mean 98. 5

Std error of mean 0. 777

Assuming the life length of batteries is normally distributed, if you wish to conduct this test at the 0. 05 level of significance, what are the critical values that you should use? Place the smaller critical value, rounded to 3 decimal places, in the first blank. For example, -1. 234 would be a legitimate entry. Correct-2. 093 . Place the larger critical value, rounded to 3 decimal places, in the second blank. For example, 1. 234 would be a legitimate entry. Correct2. 093

Answer Key: -

Question 14 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A medical doctor wishes to test the claim that the standard deviation of the systolic blood pressure of deep sea divers is less than 450. To do so, she selected a random sample of 20 divers and found s = 432.

Assuming that the systolic blood pressures of deep sea divers are normally distributed, if the doctor wanted to test her research hypothesis at the . 01 level of significance, what is the critical value?

Place your answer, rounded to 3 decimal places, in the blank. For example, 4. 567 would be a legitimate entry. Correct7. 633

Answer Key:

Question 15 of 20

0. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

Suppose a firm that produces light bulbs wants to know whether it can say that its light bulbs typically last more than 1500 hours. Hoping to find support for their claim, the firm collects a random sample of n = 25 light bulbs and records the lifetime (in hours) of each bulb. The information related to the hypothesis test is presented below.

Test of H0: f$mu leq f$ 1500 versus H1: f$ mu f$ > 1500

Sample mean 1509. 5

Std error of mean 4. 854

Assuming the life length of this type of lightbulb is normally distributed, what is the p-value associated with this test? Place your answer, rounded to 3 decimal places in the blank. For example, . 123 would be a legitimate entry. Correct1. 711

Answer Key

Question 16 of 20

1. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

The ABC battery company claims that their batteries last at least 100 hours, on average. Your experience with their batteries has been somewhat different, so you decide to conduct a test to see if the company's claim is true. You believe that the mean life is actually less than the 100 hours the company claims. You decide to collect data on the average battery life (in hours) of a random sample of n = 20 batteries. Some of the information related to the hypothesis test is presented below.

Test of H0: f$mu geq f$ 100 versus H1: f$mu< f$ 100

Sample mean 98. 5

Std error of mean 0. 777

Assuming the life length of batteries is normally distributed, what is the p-value associated with this test? Place your answer, rounded to 3 decimal places in the blank. For example, 0. 0234 would be a legitimate entry. Correct. 0344

Answer Key:

Question 17 of 20

0. 0/ 1. 0 Points

Accepted characters: numbers, decimal point markers (period or comma), sign indicators (-), spaces (e. g. , as thousands separator, 5 000), "E" or "e" (used in scientific notation). NOTE: For scientific notation, a period MUST be used as the decimal point marker.

Complex numbers should be in the form (a + bi) where "a" and "b" need to have explicitly stated values.

For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not.

A statistician wishes to test the claim that the standard deviation of the weights of firemen is greater than 25 pounds. To do so, she selected a random sample of 30 firemen and found s = 27. 2 pounds.

Assuming that the weights of firemen are normally distributed, if the statistician wanted to test her research hypothesis at the . 05 level of significance, what is the critical value?

Place your answer, rounded to 3 decimal places, in the blank. For example, 23. 456 would be a legitimate entry. Correct34. 329

Answer Key:

Part 3 of 3 - 3. 0/ 3. 0 Points

Question 18 of 20

1. 0/ 1. 0 Points

Sample evidence is statistically significant at the f$alpha f$ level only if the p–value is larger than f$alpha f$ .

Correct

True

False

Answer Key:

Question 19 of 20

1. 0/ 1. 0 Points

If a null hypothesis about a population mean is rejected at the 0. 025 level of significance, then it must also be rejected at the 0. 01 level.

Correct

True

False

Answer Key:

Question 20 of 20

1. 0/ 1. 0 Points

A low p–value provides evidence for accepting the null hypothesis and rejecting the alternative.

Correct

True

False

Answer Key: