Suppose there is a correlation of r = 0.9 between number of hours per day students study and GPAs. Which of the following is a reasonable conclusion?
(A)90% of students who study receive high grades. (B)90% of students who receive high grades study a lot. (C)90% of the variation in GPAs can be explained by variation in number of study hours per day. (D)81% of the variation in GPAs can be explained by variation in number of study hours per day.
D