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) Which variable is X and which variable is Y in this situation?

b) What meaning (if any) does the y intercept of 20 have in this situation?