Question
A study is conducted to estimate the average difference in bus use in a large city between the morning and afternoon rush hours. The transit authority's researcher randomly selects nine buses because of the variety of routes they represent. On a given day, the number of passengers on each bus is counted at 7.45 am and at 4.45 pm, with the following results:
| Bus |
Morning |
Afternoon |
| 1 |
43 |
41 |
| 2 |
51 |
49 |
| 3 |
37 |
44 |
| 4 |
24 |
32 |
| 5 |
47 |
46 |
| 6 |
44 |
42 |
| 7 |
50 |
47 |
| 8 |
55 |
51 |
| 9 |
46 |
49 |
|
|
|
|
|
|
| Sample size |
9 |
|
| Confidence interval |
90% |
|
a) Use the data to compute a 90% confidence interval to estimate the population average difference. Assume that the number of passengers is normally distributed.