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1. Confidence intervals are useful when trying to estimate _______.

a. unknown parameters

b. known parameters

c. unknown statistics

d. known statistics

2. The one-sample z statistic is used instead of the one-sample t statistic when ______.

a. is known

b. is unknown

c. is known

d. is unknown

3. The ____ the P-value, the stronger the evidence against the null hypothesis provided by the data.

a. larger

b. smaller

4. (*) The test statistic for a two-sided significance test for a population mean is z = -2.12. What is the

corresponding P-value?

a. 0.017

b. 0.034

c. 0.483

d. 0.983

5. The probability you reject the null hypothesis when in fact the null hypothesis is true is called __________.

a. a Type I error

b. a Type II error

c. the power

6. (*) A random sample of 20 observations produced a sample mean of = 92.4 and s = 25.8. What is the

value of the standard error of ?

a. 4.6

b. 15.9

c. 1.3

d. 5.8

e. 2.6

7. (*) The heights (in inches) of adult males in the United States are believed to be Normally distributed with

mean . The average height of a random sample of 25 American adult males is found to be = 69.72

inches, and the standard deviation of the 25 heights is found to be s = 4.15. A 90% confidence interval for is

a. 69.72 1.09

b. 69.72 1.37

c. 69.72 1.42

8. Suppose we were interested in determining if there were differences in the average prices among two

local supermarkets. We randomly pick six items to compare at both supermarkets. Which statistical

procedure would be best to use for this study?

a. Matched-pairs t procedure if you interpreted as 'same six items'

b. One-sample t test

c. Two-sample t test if you interpreted as 'different six items'

d. None of the above

9. (*) Perform a one-sample t-test using the following statistics:

n = 5 = 3.871 s = 0.679

The null hypothesis is = 5.0 is

a. accepted at the 5% level; accepted at the 1% level.

b. accepted at the 5% level; rejected at the 1% level.

c. rejected at the 5% level; accepted at the 1% level.

d. rejected at the 5% level; rejected at the 1% level.

10. (*) You buy a package of 122 Smarties and 19 of them are red. What is a 95% confidence interval for the

true proportion of red Smarties?

a. (0.092, 0.220)

b. (0.103, 0.230)

c. (0.085, 0.199)