Question

To test the effect of a physical fitness course on one's physical ability, the number of sit-ups that a person could do in one minute, both before and after the course, was recorded. Ten individuals are randomly selected to participate in the course. The results are displayed in the following table. Using this data, find the 90% confidence interval for the true difference in the number of sit-ups each person can do before and after the course. Assume that the numbers of sit-ups are normally distributed for the population both before and after completing the course.

Sit-ups before	56	27	23	28	27	34	54	50	28	21
Sit-ups after	60	45	31	39	39	36	58	60	38	29

Step 1 of 4:

Find the point estimate for the population mean of the paired differences. Let x1x1 be the number of sit-ups before taking the course and x2 be the number of sit-ups after taking the course and use the formula d=x2−x1 to calculate the paired differences. Round your answer to one decimal place.

Answer 1