A research concludes that the number of hours of exercise per week for adults is

Question

A research concludes that the number of hours of exercise per week for adults is normally distributed with a mean of 4 hours and a standard deviation of 3 hours. Show all work. Just the answer, without supporting work, will receive no credit.

(a) Find the 75th percentile for the distribution of exercise time per week. (round the answer to 2 decimal places)

(b) What is the probability that a randomly selected adult has more than 7 hours of exercise per week? (round the answer to 4 decimal places)

Explanation / Answer

a. Mean =4 hours

Standard deviation = 3 hours

a. 75th perc = ?

Z = .675

75th percentile = .675*3 +4 = 6.025

b. P(X>7) = P(Z > (7-5)/3) = P(Z>.667) =1- .7454 = .2546

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