On average, do people gain weight as they age? Using data from the same study as in Exercise we provide some summary statistics for both age and weight.
(a) Calculate the least squares estimates of the slope and intercept. Graph the regression line.
(b) Use the equation of the fitted line to predict the weight that would be observed, on average, for a man who is 25 years old.
(c) Suppose that the observed weight of a 25 -year-old man is 170 lbs. Find the residual for that observation.
(d) Was the prediction for the 25 -year-old in part (c) an overestimate or underestimate? Explain briefly.