Low-profile tires are automobile tires that have a short sidewall height, which is the distance between the tire rim and the road. These tires provide better performance at the expense of gas mileage. The Ford Taurus was chosen to measure the effect these tires have on the variability of the car’s gas mileage. Ten cars of this model were selected, and the gas mileage each obtained on one tank of gas was measured using standard tires. Low-profile tires were installed on 10 other cars, and the gas mileage was again recorded.

The results are shown in the following table and can be found in the Excel file low profile variance.xlsx.

Standard Low-Profile 21.5 26.5 22.4 19.0 22.3 25.5 20.1 19.7 25.6 19.5 24.0 16.2 19.3 23.9 19.5 21.4 22.3 22.9 21.7 22.4

a. Using a = 0.05, determine if there is a difference in the variability of the mileage the two types of tires get.

b. Verify your results using PHStat.

c. Interpret the p-value obtained from the software.

AppendixLO1