Question 1

A sample of 25 account balances of a credit company showed an average balance of $4,450 with a standard deviation of $230.

1. Formulate the hypotheses that can be used to determine whether the mean of all account balances is significantly different from $4000.
2. Compute the test statistic.How do you know if you should use z or t?
3. Conduct a hypothesis test. Include all steps of hypothesis testing. Using the p-value approach, what is your conclusion? Let = .05.If you are using computer programs, you must go beyond running the program and providing the printout.You must pull out only the relevant information based on things like if this is a one-tail vs. two-tail test.

Question 2

During the recent primary elections, the democratic presidential candidate showed the following pre-election voter support in Alabama and Mississippi.

State Voters Surveyed Voters in favor of Democratic Candidate

Alabama 700 400

Mississippi 900 525

1. We want to determine whether or not the proportions of voters favoring the Democratic candidate were the same in both states. Conduct a full hypothesis test (all steps, p value approach) at 90% confidence.

Question 3

In order to estimate the difference between the yearly incomes of marketing managers in the East and West of the United States, the following information was gathered.

East West

n = 40 N = 42

X = $70,000 X= $71,500

S = 3000 S= 4000

1. Develop an interval estimate for the difference between the average yearly incomes of the marketing managers in the East and West. Use = 0.05.
2. At 95% confidence, conduct a full hypothesis test. Use the p-value approach to determine if the average yearly income of marketing managers in the East is significantly different from the West.