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?

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.