A researcher wants to know whether there is a difference between Mac users and PC users in the likelihood of getting a computer software problem. The researcher runs an experiment with two groups (Mac users and PC users) and measures the number of times they encounter a computer software problem in 3 months. Using the data below, determine if there was a difference in the likelihood of getting a computer software problem between Mac users and PC users. (Usea = .05)

	Mac users	PC users
	10	8
S2	2	3.5
n	21	21

a. State the null and alternative hypotheses in symbols. (2 points)

b. Set up the criteria for making a decision. That is, find the critical value(s). (1 point)

c. Compute the appropriate test statistic. Show your work. (3 points) Complete by NOT Pooling the Variance!

d. Based on your answers above, evaluate the null hypothesis. (1 point)

Reject Fail to reject (circle one)

e. State your conclusion in words.

f. Compute the 95% confidence interval. (2 points)

g. Interpret the confidence interval you calculated above.