Author Question: Suppose an algebra professor found that the correlation between study time (in hours) and exam score ... (Read 79 times)

jc611 · **on:** Jul 24, 2018

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. Suppose the professor later found out that his correlation was not +.80, but rather it was +.08 . How does this change the predictions he can make about exam scores based on study time?
a. You have to take the results and divide them by 10, because .80/10 = .08.
b. It won't change the predictions because the regression line stays the same.
c. The predictions should no longer be used because they won't be very accurate.
d. Not enough information to tell.

Question 2

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. For which values of study time does the professor's regression equation make sense in terms of predicting exam scores?
a. Between 0 and 20 hours.
b. Between 0 and 100 hours.
c. Anything greater than or equal to 0 hours.
d. It is not possible to predict exam score with study time.