The ages of commercial aircraft are normally distributed with a mean of 13.5 years and a standard deviation of 7.3 years. what percentage of individual aircraft have ages greater than 15 years? assume that a random sample of 49 aircraft is selected and the mean age of the sample is computed. what percentage of sample means have ages greater than 15 years?

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Mathematics

Amaris Ritter

Today, 08:42

The ages of commercial aircraft are normally distributed with a mean of 13.5 years and a standard deviation of 7.3 years. what percentage of individual aircraft have ages greater than 15 years? assume that a random sample of 49 aircraft is selected and the mean age of the sample is computed. what percentage of sample means have ages greater than 15 years?

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Anabelle Goodman · Answer 1

Answer: The percent higher is 41.68%. If 49 planes were selected, 20 of them should be above 15 years.

To find the percent, we first need the z-score.

(15 - 13.5) / 7.3 = 0.21

Now, use a normal distribution table to find the percent above a score of 0.21. It will be 41.68%.

To find the number of 49 planes above this value, multiply 49 by 0.4168. You will have about 20.4 planes.