May 9, 2009 - Extra Credit Questions

In your work groups, you will receive extra credit for each question you answer correctly (post answers under your work group):

1. In a school, 50 boys and 50 girls are randomly selected to test the claim that the mean weights for 10-year-old boys and 10-year-old girls are the same. Which of the following tests should be used in this scenario?

a) One-sample test
b) Two-sample test

2. Which of the following is a valid pair of hypotheses?
a) H0:μ1=μ2;Ha:μ1≠μ2

b) 0 1 2 1 2 : ; :a H μ >μ H μ ≤μ
c) 0 1 2 1 2 : ; :a H μ ≠μ H μ =μ
d) 0 1 2 1 2 : ; :a H μ <μ H μ ≥μ

3. To test the claim that μ1 = μ2 , two samples are randomly selected from each population. If a hypothesis test is performed, how should you interpret a decision that rejects the null hypothesis?

a) There is sufficient evidence to support the claimμ1 = μ2 .
b) There is sufficient evidence to reject the claim μ1 = μ2 .
c) There is not sufficient evidence to support the claim μ1 = μ2 .
d) There is not sufficient evidence to reject the claim μ1 = μ2 .

4. For two-sample t-tests for small independent samples, the following condition or
conditions have to be met:

a) The samples must be randomly selected.
b) The samples must be independent.
c) Each population must have a normal distribution.
d) Each population must have a t-distribution.

5. For a two-sample t-test, if the test statistic is outside the rejection region, or regions, which of the following decisions should be made?

a) Fail to reject the alternative hypothesis.
b) Reject the alternative hypothesis.
c) Fail to reject the null hypothesis.
d) Reject the null hypothesis.

6. Two samples are considered independent if the sample selected from one population is not related to the sample selected from the second population.

a) True
b) False

7. For a two-sample hypothesis test, the alternative hypothesis is a statistical hypothesis that is reasonable when the null hypothesis is not accepted.

a) True
b) False

8. When doing 2 sample hypothesis tests, which of the following tests would you conduct if the samples sizes are less than 30, the populations are normal, the standard deviations are unknown, and the population variances are equal?

a) z-Test
b) t-Test

9. Given H0: μ1 ≥ μ2 , critical value t0 = −1.350, and standardized test statistic
t = −4.038 , you will:

a) Reject the null hypothesis.
b) Fail to reject the null hypothesis.

10. A crash test claims that the mean bumper repair cost for small cars is less than that for midsize cars. After conducting a t-test, a decision is made to reject the null hypothesis at the 5% level. The decision implies that:

a) There is enough evidence at the 5% level to support the claim that the mean bumper
repair cost is less for small cars than it is for midsize cars.
b) There is insufficient evidence at the 5% level to support the claim that the mean bumper repair cost is less for small cars than it is for midsize cars.
c) There is insufficient evidence at 5% level to reject the claim that the mean bumper repair cost is less for small cars than it is for midsize cars.
d) There is enough evidence at the 5% level to reject the claim that the mean bumper repair cost is less for small cars than it is for midsize cars.