Point estimation-standard error-multiple 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 8-2. 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 8-2. 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 9-4. The standardized test statistic is

a. 1.96

b. 1.64

c. 2.00

d. 0.056

B. Refer to Exhibit 9-4. The p-value 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.