## Section A: Short Answer Questions and Fill in the BlankQuestions (60 points). 1.

Section A: Short Answer Questions and Fill in the BlankQuestions (60 points). 1. A study by a bank compared the averagesavings of customers who were depositors for three years or lesswith those who had been depositors for more than three years. Theresults of a sample are: Assuming that the financial officer wantsto show that there is a difference in the average savings balancebetween the two classes of depositors what is the null hypothesis?_____________________ 2. If we are testing for the differencebetween two population means and assume that the two populationshave equal but unknown standard deviations then the test has_________ degrees of freedom. 3. The pooled estimate of theproportion is found by dividing the total number of successes by__________________________. 4. If we are testing for the differencebetween two population means and assume that the two populationshave equal and unknown standard deviations the standard deviationsare _____. 5. When independent samples with unknown but equalstandard deviations are used to test for differences in the meanswe pool the sample ________________. 6. The paired t test isespecially appropriate when the sample sizes of two groups are_______. 7. The paired difference test has ___________ degrees offreedom. 8. When testing the difference between two populationmeans the hypothesized difference is _______________. 9. Whentesting the difference between two population proportions thehypothesized difference is _______________. 10. A statisticsprofessor wants to compare grades in two different classes of thesame course. This is an example of _________ populations. SectionB: Hypothesis Testing (40 points). 11. A financial planner wants tocompare the yield of income and growth mutual funds. Fifty thousanddollars is invested in each of a sample of 35 income and 40 growthfunds. The mean increase for a two-year period for the income fundsis \$900. For the growth funds the mean increase is \$875. Incomefunds have a sample standard deviation of \$35; growth funds have asample standard deviation of \$45. Assume that the populationstandard deviations are equal. At the 0.05 significance level isthere a difference in the mean yields of the two funds? Whatdecision is made about the null hypothesis using and a = 0.05?____________ 12. A company is researching the effectiveness of anew web site design to decrease the time to access a website. Fiveweb site users were randomly selected and their times (in seconds)to access the web site with the old and new designs were recorded.The results follow.