Toyota Prius Gas Mileage. Use the following information for Exercises 60–67. Cars.com reported in 2014 that the mean city/highway combined gas mileage for the Toyota Prius hybrid car was 50 mpg. This year, a random sample of 16 Toyota Prius cars had the gas mileages shown here (in miles per gallon (mpg)). Assume . The research question is to test whether mean gas mileage has increased since 2014.
507
| 48.1 | 49.9 | 50.6 | 51.8 |
| 48.8 | 50.0 | 50.9 | 52.2 |
| 49.3 | 50.2 | 51.3 | 52.9 |
| 49.5 | 50.4 | 51.6 | 53.9 |
67. Note the contradiction in your conclusions from Exercises 64 and 66. Can you suggest any way to resolve this?
9.2.67
Turn to a direct assessment of the strength of evidence against the null hypothesis or obtain more data.