CAS Ex-300 ES PL NATURAL 42. Suppose there is a correlation of r = 0.9 between number of hours per day the students study and GPAs. Which of the following is a reasonable conclusion? (a) 90% of the students who study receive high grades. (b) 90% of the students who receive high grades study a lot. 90% of the variation in GPAs can be explained by the linear regression model of GPA on the number of study hours. (d) 81% of the variation in GPAs can be explained by the linear regression model of GPA on the number of study hours. 95% of the variation in GPAs can be explained by the linear regression model of GPA on the number of study hours. 43. The Test of English as a Forcign Language Skills (TOEFL) scores are approximately normally distributed with a mean of 540 and standard deviation of 60. Using the Empirical Rule (the 68-95-99.7% Rule), approximately, what percentage of the TOEFL scores are between 480 and 660? 82 percent mea - 540 (b) 68 percent SP - 60 68 95 99- 7 (c) 95 percent (d) 34 percent - 540 + (60) = 540-2160) = 540 3(50) = 480 (c) 48 percent : 650 + = 500 = 420 44. Cholesterol levels (denoted by X) of the patients at a doctor's office have a Normal distribution with mean 229 mg/dL and standard deviation 40 mg/dL. What is the value of k such that P(X > 277) = P(X