Testing tires for wear. Underinflated or overinflated tires can increase tire wear. A new tire was tested for wear at different pressures, with the results shown in the following table.

Pressure x (pounds per square inch)

Mileage y

(thousands)

30 29 31 32 32 36 33 38 34 37 35 33 36 26

a. Plot the data on a scatterplot.

b. If you were given only the information for x = 30, 31, 32, and 33, what kind of model would you suggest? For x = 33, 34, 35, and 36? For all the data?