Devry MATH221 2020 April Week 7 Quiz Latest

MATH221 Statistics for Decision Making

Week 7 Quiz   

Question 1 (CO 4) From a random sample of 55 businesses, it is found that the mean time that employees spend on personal issues each week is 5.8 hours with a standard deviation of 0.35 hours. What is the 95% confidence interval for the amount of time spent on personal issues?

  (5.71, 5.89)

  (5.74, 5.90)

  (5.72, 5.88)

  (5.73, 5.87)

Question 2 (CO 4)If a confidence interval is given from 8.50 to 10.25 and the mean is known to be 9.375, what is the margin of error?

  8.500

  1.750

  0.875

  0.438

Question 3 (CO 4) Which of the following is most likely to lead to a large margin of error?

  large sample size

  small sample size

  small standard deviation

  small mean

Question 4 (CO 4) From a random sample of 41 teens, it is found that on average they spend 31.8 hours each week online with a population standard deviation of 3.65 hours. What is the 90% confidence interval for the amount of time they spend online each week?

  (28.15, 35.45)

  (24.50, 39.10)

  (30.86, 32.74)

  (29.99, 33.61)

Question 5 (CO 4) A company making refrigerators strives for the internal temperature to have a mean of 37.5 degrees with a population standard deviation of 0.6 degrees, based on samples of 100. A sample of 100 refrigerators have an average temperature of 37.37 degrees. Are the refrigerators within the 90% confidence interval?

  Yes, the temperature is within the confidence interval of (37.40, 37.60)

  No, the temperature is outside the confidence interval of (36.90, 38.10)

  Yes, the temperature is within the confidence interval of (36.90, 38.10)

  No, the temperature is outside the confidence interval of (37.40, 37.60)

Question 6 (CO 4) What is the 97% confidence interval for a sample of 104 soda cans that have a mean amount of 12.10 ounces and a population standard deviation of 0.08 ounces?

  (12.035, 12.065)

  (12.020, 12.180)

  (12.083, 12.117)

  (12.033, 12.067)

Question 7 (CO 4) Determine the minimum sample size required when you want to be 98% confident that the sample mean is within two units of the population mean. Assume a population standard deviation of 4.82 in a normally distributed population.

  32

  31

  33

  34

Question 8 (CO 4) Determine the minimum sample size required when you want to be 80% confident that the sample mean is within one unit of the population mean. Assume a population standard deviation of 9.24 in a normally distributed population.

  141

  195

  231

  36

Question 9 (CO 4) Determine the minimum sample size required when you want to be 75% confident that the sample mean is within twenty units of the population mean. Assume a population standard deviation of 327.8 in a normally distributed population

  1422

  727

  356

  557

 

Question 10 (CO 4) In a sample of 8 high school students, they spent an average of 25.8 hours each week doing sports with a sample standard deviation of 3.2 hours. Find the 95% confidence interval, assuming the times are normally distributed.

  (23.15, 28.50)

  (22.60, 29.00)

  (23.12, 28.48)

  (19.40, 32.20)