Suppose that the distribution of scores on the Graduate Record Exam (GRE) is approximately normal, with a mean of u = 150 and a standard deviation of o = 5. For the population of students who have taken the GRE: a. What proportion have GRE scores less than 145? b. What proportion have GRE scores greater than 157? c. What is the minimum GRE score needed to be in the highest 20% of the population? d. If a graduate school accepts only students from the top 10% of the GRE distribution, what is the mini- mum GRE score needed to be accepted