In a test of the effectiveness of a device that is supposed to increase gasoline mileage in automobiles, 12 cars were run over a prescribed course both with and without the device. The mileages are given below.
| Car |
with device |
without device |
| 1 |
21 |
20.6 |
| 2 |
30 |
29.9 |
| 3 |
29.8 |
30.7 |
| 4 |
27.3 |
26.5 |
| 5 |
27.7 |
26.7 |
| 6 |
33.1 |
32.8 |
| 7 |
18.8 |
21.7 |
| 8 |
26.2 |
28.2 |
| 9 |
28 |
28.9 |
| 10 |
18.9 |
19.9 |
| 11 |
29.3 |
32.4 |
| 12 |
21 |
22 |
What test should be used?
a) Chi-Square Goodness-of-Fit test
b) Chi-Square Test of Independence
c) Paired-t Test
d) Pooled-t test