Question

An instructor at the U.S. Navy’s underwater demolition school believes she has developed a new technique for staying underwater longer. As part of their qualifying exam, all students are tested to see how long they can stay underwater without an air tank. Past records show that the scores are normally distributed with a mean of 130 seconds and a standard deviation of 14 seconds. If the new technique has no additional effect, what is the probability that a randomly selected newly trained student will stay underwater for

a. Over 150 seconds?

b. Between 115 and 135 seconds?

c. Less than 90 seconds?

d. What is the minimum time that the top 5% of students stay underwater?

Answer 1