Linear Regression Exercises Problem 3. Two researchers are investigating the effects of time spent studying on the exam marks earned by students on a certain course. For a sample of 100 students, they have the exam mark, M , total hours spent studying, H, hours on primary study, P, and hours spent on revision, R. By definition, H = P + R. Researcher A decides to regress M on P and R and fits the following regression: M = 45.6 + 0.15P + 0.21R. Researcher B decides to regress M on H and P, with regression output M = 45.6 + 0.21H - 0.06P. Give an interpretation of the coefficients of both regressions. [2p]