A philosophy professor has found a correlation of 0.80 between the number of hours students study for his exams and their exam performance. During the time he collected the data, students studied an average of 10 hours with a standard deviation of 2.5 hours, and scored an average of 80 points with a standard deviation of 7.5 points.
a. Using the techniques given in the text for exercises 15.35 - 15.37 calculate the equation for the least squares regression equation predicting the number of points a student will score on the next exam from the number of hours the student studies
b. If a student studies for 15 hours, what score should the student expect on the next
c. What percent of the variation in the points earned on the exam is explained by the number of hours the student studies?