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 99% 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	42	22	21	44	30	47	39	46	34	33
Sit-ups after	60	33	32	52	34	51	48	57	45	41

Step 1 of 4 :  

Find the point estimate for the population mean of the paired differences. Let x1 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.

Step 2 of 4:

Calculate the sample standard deviation of the paired differences. Round your answer to six decimal places.

Step 3 of 4:

Use the 99% confidence interval for the true difference between the population means. Assume that both populations are normally distributed.

Step 4 of 4:

Construct the 99% confidence interval. Round our answers to one decimal places.

Answer 1