Question

the average age of a vehicle registerd in the united state in 8 year or 96 month . assume the standard deviation is 16 month .if random sample 36 month is selected .find the probabilty that the mean of their age a. betwen 90 and 100

Answer 1

Answer: The average age of a vehicle registered in the United States is 8 years or 96 months. Assume the standard deviation is 16 months. If a random sample of 36 vehicles is selected, find the probability that the mean of their age is between 90 and 100 months.

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Find the t-scores of 90 and 100.

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t(90) = (90-96)/[16/sqrt(36)]

= -6/(16/6) = - 2.25

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t(100) = (100-96)/[16/36)] = 4*6/16 = 1.5

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P(90 < t-bar < 100) = P(-2.25< t < 1.5) = tcdf(-2.25,1.5,35) = 0.9133

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Muhammad Zayaan Yasir

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