Researchers continue to look for methods to measure how fast a car was traveling before an accident. Most methods focus on the distance, d (in feet) required for an average car to completely stop while traveling at various speeds, s. Consider the table below.

MPH(s) 30 40 50 60 70 80

Braking Distance(d) 45 80 125 180 245 320

a) Use the LinReg command in your graphing calculator and report the linear regression model for this data rounded to one decimal place. (Be sure to write the linear model as an equation and don't forget to put a "hat" over the predicted variable.)

b) Identify and interpret the slope of the linear regression model you found in part (a).

c) Use the model to predict the braking distance for a car traveling 65 mph.

d) What is the observed braking distance for a car traveling 50 mph? What is the predicted distance for a car traveling 50 mph?

e) Find the residual for a car traveling 50 mph.

f) Interpret, in the context of the problem, the residual you found in part (d).