Study Time and Score. An instructor at Arizona State University asked a random sample of 10 students to record their study times in a beginning statistics course. She then made a table for total hours studied (x) over 2 weeks and test score (y) at the end of the 2 weeks. Here are the results.

x 12 24 10 9 15 17 9 18 16 22 y 84 79 81 90 81 85 82 84 83 75 In Exercises 15.28–15.33,

a. compute the standard error of the estimate and interpret your answer.

b. interpret your result from part

(a) if the assumptions for regression inferences hold.

c. obtain a residual plot and a normal probability plot of the residuals.

d. decide whether you can reasonably consider Assumptions 1–3 for regression inferences to be met by the variables under consideration. (The answer here is subjective, especially in view of the extremely small sample sizes.)