Previous Next Question 3 of 8 (1 point) Mew problem in a popup Going to Work: Th

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Previous Next Question 3 of 8 (1 point) Mew problem in a popup Going to Work: The mean distance that commuters in a city travel each way to work is 18 miles. Assume the standard deviation is9 miles. A sample of 76 commuters is chosen. Use the TH-84calculator to answer the following. Part 1 What is the probability that the sample mean commute distance is greater than 15 miles? Round the answer to four decimal places. The probability that the sample mean commute distance is greater than 15 miles is 0.6306 Correct answer: 0.9982 Part 2 What is the probability that the sample mean commute distance is between 21 and 25 miles? Round the answer to four decimal places. The probability that the sample mean commute distance is between 21 and 25 miles is 0.1511 Correct answer: 0018 Part 3 Find the 20th percentile of the sample mean. Round the answer to two decimal places. The 20th percentile of the sample mean is .13 miles. Essential statistics is Course ath1107 Spring2017 Jay Lindsay

Explanation / Answer

mean = 18
std. dev = 9
n = 76

Part 1:
P(X>15) = P(z>(15-18)/(9/sqrt(76))) = P(z > -2.9059) = 0.9982

Part 2:
P(21<X<25) = P((21-18)/(9/sqrt(76))< z < (25-18)/(9/sqrt(76))) = P(2.9059 < z < 6.7805) = 0.0018

Part 4:
As probability computed for mean > 21 is 0.0018, it would be unusual for the sample mean to be greater than 21.

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