Research studies show that the relationship between the tire pressure of a vehicle’s tires and the life of the tires is quadratic. The following table shows the recommended tire pressure of a car’s tires (in pounds per square inch) and its anticipated tire life (in thousands of miles).
Tire Pressure Tire Life
29 46.8
32 57.6
34 58.8
36 60.0
38 58.8
40 57.0
42 52.8
Use a graphing or online regression calculator to find the quadratic function of best fit for this set of data. What is the value of a in this function?
-0.240947
-2.40947
-0.00240947
-0.0240947