Question

In: Statistics and Probability

Week 4 11 of 12 The ages of commercial aircraft are normally distributed with a mean...

Week 4 11 of 12

The ages of commercial aircraft are normally distributed with a mean of 13.5 years and a standard deviation of 6.6627 years. What percentage of individual aircraft have ages between 11 years and 16 years? Assume that a random sample of 81 aircraft is selected and the mean age of the sample is computed. What percentage of sample means have ages between 11 years and 16years?

The percentage of individual aircraft that have ages between 11 years and 16 years is

__________________

​(Round to the nearest integer as​ needed.)

The percentage of sample means that have ages between 11 years and 16 years is

_________________

​(Round to the nearest tenth as​ needed.)

Solutions

Expert Solution

µ = 13.5

sd = 6.6627

                                    
                                     = P(-0.38 < Z < 0.38)

                                     = P(Z < 0.38) - P(Z < -0.38)

                                     = 0.6480 - 0.3520

                                     = 0.2960

                                     = 30%

                                    

                                     = P(-3.38 < Z < 3.38)

                                     = P(Z < 3.38) - P(Z < -3.38)

                                     = 0.9996 - 0.0004

                                     = 0.9992


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