Suppose the variables and time are related according to the simple linear regression model with .

a. If observations are made at the x values x1 5 5, x2 5 10, x2 5 15, x2 5 20, and , calculate the standard deviations of the five corresponding residuals.

b. Repeat part

(a) for , and . x 5 5 50 x 1 5 5, x 2 5 10, x 3 5 15, x 4 5 20 x 5 5 25 n 5 5 s 5 10 y 5 com

c. What do the results of parts

(a) and

(b) imply about the deviation of the estimated line from the observation made at the largest sampled x value?