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The taxi and takeoff time for commercial jets is a random variable x with a mean of 8.4 minutes and a standard deviation of 3.5 minutes. Assume that the distribution of taxi and takeoff times is approximately normal. You may assume that the jets are lined up on a runway so that one taxies and takes off immediately after the other, and that they take off one at a time on a given runway.What is the probability that for 37 jets on a given runway, total taxi and takeoff time will be less than 320 minutes?

User Michele
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Answer:

0.6672 is the required probability.

Explanation:

We are given the following information in the question:

Mean, μ = 8.4 minutes

Standard Deviation, σ = 3.5 minutes

We are given that the distribution of distribution of taxi and takeoff times is a bell shaped distribution that is a normal distribution.

According to central limit theorem the sum measurement of n is normal with mean
\mu and standard deviation
\sigma√(n)

Sample size, n = 37

Standard Deviation =


=\sigma* √(n) = 3.5* √(37)=21.28

P(taxi and takeoff time will be less than 320 minutes)


P( \sum x < 320) = P( z < \displaystyle(320 - 37(8.4))/(21.28)) = P(z < 0.4323)

Calculation the value from standard normal z table, we have,


P(\sum x < 320) =0.6672 = 66.72\%

0.6672 is the probability that for 37 jets on a given runway, total taxi and takeoff time will be less than 320 minutes.

User Studentbi
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