An environmental group is interested in studying the effects of engine size (cubic inches) on the gas mileage of cars (mpg). consider the following data collected to determine the effect of engine size (cubic inches) on the gas mileage of cars (mpg).
| Gas mileage (mpg) |
Engine size (cubic inches) |
| 18.9 |
350 |
| 17.00 |
350 |
| 20.00 |
250 |
| 18.25 |
351 |
| 20.27 |
225 |
| 11.2 |
440 |
| 22.12 |
231 |
| 21.47 |
262 |
| 34.70 |
89.7 |
| 30.4 |
96.9 |
| 16.5 |
350 |
| 36.5 |
85.3 |
| 21.5 |
171 |
| 19.7 |
258 |
| 20.3 |
140 |
| 17.8 |
302 |
| 14.39 |
500 |
| 14.89 |
440 |
| 17.8 |
350 |
| 16.41 |
318 |
| 23.54 |
231 |
| 21.47 |
360 |
| 16.59 |
400 |
| 31.9 |
96.9 |
| 29.4 |
140 |
| 13.27 |
460 |
| 23.9 |
133.6 |
| 19.73 |
318 |
| 13.90 |
351 |
| 13.27 |
351 |
| 13.77 |
360 |
| 16.5 |
350 |
A) Draw a scatter plot of the data. Do you think a straight line would be a good fit of this data?
B) Fit a simple linear regression model to the above data that shows how engine size affects gas mileage.
C) Does engine size significantly affect gas mileage? YES or NO? use α = 0.05. How do you know this? What part of you Excel or Minitab output helped you answer this question?
D) using your regression line predict the gas mileage when the engine size is 275 cubic inches.