It has been found that times taken by people to complete a particular tax form follow a normal distribution with a mean of 100 minutes and a standard deviation of 30 minutes. A random sample of nine people who have completed this tax form was taken. a. What is the probability that the sample mean time taken is more than 120 minutes? b. The probability is 0.20 that the sample mean time taken is less than how many minutes? c. The probability is 0.05 that the sample standard deviation of time taken is less than how many minutes?

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 19PFA
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It has been found that times taken by people to complete a particular tax form follow a normal distribution with a mean of 100 minutes and a standard deviation of 30 minutes. A random sample of nine people who have completed this tax form was taken.
a. What is the probability that the sample mean time taken is more than 120 minutes?
b. The probability is 0.20 that the sample mean time taken is less than how many minutes?
c. The probability is 0.05 that the sample standard deviation of time taken is less than how many minutes?

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