V ades in an introductory statistics course is normally distributed, with a mean of 72 and a standard deviation of 8. Complete parts (a) through (d). a. What is the probability that a student scored below 84 on this exam? The probability that a student scored below 84 is (Round to four decimal places as needed.) b. What is the probability that a student scored between 64 and 89? The probability that a student scored between 64 and 89 is (Round to four decimal places as needed.) c. The probability is 15% that a student taking the test scores higher than what grade? The probability is 15% that a student taking the test scores higher than (Round to the nearest integer as needed.) d. If the professor grades on a curve (for example, the professor could give A's to the top 10% of the class, regardless of the score), is a student better off with a grade of 80 on the exam with a mear of 72 and a standard deviation of 8 or a grade of 68 on a different exam, where the mean is 62 and the standard deviation is 3? Show your answer statistically and explain. A student is with a grade of 80 on the exam with a mean of 72 and a standard deviation of 8 because the Z value for the grade of 80 is and the Z value for the grade of 68 on the different exam is (Round to two decimal places as needed.)