Question:

The golf professional at a private course claims that members who have taken lessons from him lowered their handicaps by more than 5 strokes. The club manager decides to test the claim by randomly sampling 25 members who have had lessons and asks each to report their reduction in handicap. These data are stored in file Xr11-45 on the student CD. A negative number represents an increase in handicap. Assuming that the reduction in handicap is approximately normally distributed with a standard deviation of 2 strokes, test the golf professional’s claim using a 10% significance level.