The following table presents the speed (in mph) and the stopping distance (in feet) for a sample of cars.

x = Speed	4	7	8	9	10	11	12	13	14	15
x2
y = Distance	12	14	19	20	18	22	25	32	38	38

x = Speed	16	17	18	19	20	22	23	24	25
x2
y = Distance	44	48	49	57	59	75	78	87	90

A) Compute the least-squares regression line for predicting stopping distance (y) from speed (x) and record it below.

B) Construct a residual plot in Statdisk. Explain why the least-squares regression line is not an appropriate summary of the data. (You do not need to submit the residual plot.)

C) For each data point, square the speed and record this (x2) in the table above. Compute the least-squares regression line for predicting stopping distance y from speed x2 and record it below.

D) Construct a residual plot in Statdisk. Is this line an appropriate summary?

(You do not need to submit the residual plot.)

E) Use the equation computed in part (c) to predict the stopping distance for a car whose speed is 15 mph.