Point estimationstandard errormultiple regression equation
1. A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.22 ounces. The point estimate of the mean content of the bottles is:
a. 0.22
b. 4
c. 121
d. 0.02
2. There are 6 children in a family. The number of children defines a population. The number of simple random samples of size 2 (without replacement) that are possible equals:
a. 12
b. 15
c. 3
d. 16
3. A random sample of 81 automobiles traveling on an interstate showed an average speed of 60 mph and a standard deviation of 13.5 mph. Assume the distribution of speeds of all the cars is normal.
A. Refer to Exhibit 82. If we are interested in determining an interval estimate for m at 86.9% confidence, the Z value to use is
a. 1.96
b. 1.31
c. 1.51
d. 2.00
B. Refer to Exhibit 82. The standard error of the mean is
a. 13.5
b. 9
c. 2.26
d. 1.5
4. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took the customers in the sample to check out was 3.1 minutes with a standard deviation of 0.5 minutes. We want to test to determine whether or not the mean waiting time of all customers is significantly more than 3 minutes.
A. Refer to Exhibit 94. The standardized test statistic is
a. 1.96
b. 1.64
c. 2.00
d. 0.056
B. Refer to Exhibit 94. The pvalue is
a. 0.025
b. 0.0456
c. 0.05
d. 0.0228
5. Which of the following statements is not a required assumption for developing an interval estimate of the difference between two sample means when the samples are small?
a. Both populations have normal distributions.
b. s1 = s2 = 1
c. Independent random samples are selected from the two populations.
d. The variances of the two populations are equal.

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