In How It Works 15.2, we calculated the correlation coefficient between students’ age and number of hours they study per week. The mean for age is 21, and the standard deviation is 1.789. The mean for hours studied is 14.2, and the standard deviation is 5.582. The correlation between these two variables is 0.49. Use the z score formula.

a. João is 24 years old. What would we predict for the number of hours he studies per week?

b. Kimberly is 19 years old. What would we predict for the number of hours she studies per week?

c. Seung is 45 years old. Why might it not be a good idea to predict how many hours per week he studies?

d. From a mathematical perspective, why is the word regression used? [Hint: Look at parts

(a) and

(b), and discuss the scores on the first variable with respect to their mean versus the predicted scores on the second variable with respect to their mean.]