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 1 minute, both before and after the course, was recorded. Ten randomly selected participants scored as shown in the following table. Can you conclude that a significant amount of improvement took place? Use ? = 0.01 and assume normality.
| Before |
14 |
15 |
13 |
13 |
11 |
15 |
17 |
17 |
15 |
15 |
| After |
18 |
22 |
13 |
23 |
17 |
18 |
20 |
25 |
22 |
16 |
(a) Find t. (Give your answer correct to two decimal places.)