Suppose an algebra professor found that the correlation between study time (in hours) and exam score (out of 100) is +.80, and the regression line was found to be y = 20 + 4x. He arrived at this equation through years of collecting data on his students, most of whom reported studying anywhere from 0 to 20 hours for his exams.

a. What meaning (if any) does the slope of 4 have in this situation?

b. In order to get an 80 on this exam, how long should students expect to study?