In How It Works 13.2, we calculated the correlation coefficient between students’ age and number of hours they study per week. The correlation between these two variables is 0.49. 

a. Elif ’s z score for age is −0.82. What would we predict for the z score for the number of hours she studies per week? 

b. John’s z score for age is 1.2. What would we predict for the z score for the number of hours he studies per week? 

c. Eugene’s z score for age is 0. What would we predict for the z score for the number of hours he studies per week? 

d. For part (c) explain why the concept of regression to the mean is not relevant (and why you didn’t really need the formula).