# Normal distribution probabilities

Scores on the Graduate Management Admission Test (GMAT) are normally distributed with a mean of 500 and a standard deviation of 80.

a. Find the probability that a randomly selected test-taker will score at least 640 on the GMAT.

b. Find the probability that a randomly selected test-taker will score between 420 and 640.

c. Suppose 16 students take the GMAT. Find the probability that the sample average score will be at or below 600.

d. Graduate Record Examination (GRE) scores are normally distributed with a mean of 1,000 and a standard deviation of 180. Suppose Amy earned a score of 1,450 on the GRE, and her brother Bill scored 740 on the GMAT. Who earned the higher score?

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#### Solution Summary

This solution shows how to find probabilities from a known normal probability distribution.