Question

Gas Mileage

The cost of fuel is largest component of cost of ownership for most vehicles. Fuel cost is (almost) inversely proportional to gas mileage; higher gas mileage means lower fuel cost and vice-versa. If you keep track of the number of miles driven on each tank of gas as well as how much gas is purchased, it is easy to calculate gas mileage; many cell phone apps exist to track this. The data on the second page is the gas mileage for one of Mr. Hebert’s cars taken over the past year.

Find the average fuel economy. Find the standard deviation for this sample.

Find the 5-number summary. Construct a box-and-whiskers plot of this data.

Does it show any skew or symmetry?

Set up a 95% Confidence Interval to estimate the average fuel economy of the vehicle.

The manufacturer (by way of the EPA) prints city, highway, and combined fuel economy on the window sticker of each new car.

Find the combined fuel economy rating for the vehicle (you may find the website www.fueleconomy.gov to be helpful here).

From the point of view of Mr. Hebert’s credit card bill, getting less than the specified gas mileage would be troublesome and annoying. Based on that information, determine the null and alternative hypotheses. Would this be a one-tailed hypothesis test or a two-tailed test?

Test whether the Mr. Hebert is getting ripped off at the a = 0.05 level of significance.

Is Mr. Hebert getting the claimed fuel economy? Discuss reasons why the measured fuel economy may be different from the manufacturer’s claim.

Vehicle Information: 2015 Jeep Wrangler Unlimited with 3.6L V6 and 5-speed automatic transmission

19.07

20.91

21.17

22.11

15.36

15.12

17.09

16.8

18.17

18.27

17.66

18.86

14.71

15.65

13.48

13.28

12.85

14.65

14.98

16.41

15.11

15.13

17.5

15.14

15.62

Answer 1

ANSWER :-