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%

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 Sit-ups after

22 25

49 58

25 36

44 46

45 53

20 38

35 45

42 49

42 53

33 35

Step1of4:Find the point estimate for the population mean of the paired differences. Letx

1

x1be the number of sit-ups before taking the course andx

2

x2be the number of sit-ups after taking the course and use the formulad=x

2

x

1

d=x2x1to calculate the paired differences. Round your answer to one decimal place.