1. A company wanted to know if attending a course on "how to be a successful salesperson" can increase the average sales of its employee. The company sent five of its salespersons to attend this course. The following table gives the one-week sales of these salespersons before and after they attended this course.

Before 12 18 22 12 16

After 16 20 23 11 19

Can you conclude that the mean weekly sales for all salespersons increase as a result of attending this course ? (a) (3 points) State the null hypothesis and alternative hypothesis

(b) Find the test statistic

(c) If the type-I error = 0.05, find the critical value(s) and shade the rejection region(s)

(d) Base on the type-I error and rejection region(s), given above, what is your conclusion?

2. A team of eye surgeons has developed a new technique for risky eye operation to restore the sight of people blinded from certain disease. Under the current method, it is known that only 30% of patients who undergo this operation recover their eyesight.

Suppose the surgeons in various hospitals have performed a total od 225 operations using new method and that 88 have been successful. Can we justify the claim that the new method is better than the current method?

(a) State the null hypothesis and alternative hypothesis

(b) Find the test statistic

(c) If the type-I error = 0.05, find the critical value(s) and shade the rejection region(s) (d) (2 points) Base on the type-I error and rejection region(s), given above, what is your conclusion?

3. Generally speaking, would you say that most people can be trusted? A random sample of n1 = 250 freshman students in the WEP university showed that x1 = 45 say yes. Another random sample of n2 = 280 senior students in WEP university showed that x2 = 71 say yes. Does this indicate that the population proportion of trusting people in the WEP university is higher for senior groups?

(a) State the null hypothesis and alternative hypothesis

(b) Find the test statistic

(c) If the type-I error = 0.05, find the critical value(s) and shade the rejection region(s)

(d) Base on the type-I error and rejection region(s), given above, what is your conclusion