The amount of fuel used by jumbo jets to take off is normally distributed with a mean of 4000 gallons and a standard deviation of 125 gallons. What is the probability that the mean number of gallons of fuel needed to take off for a randomly selected sample of 40 jumbo jets will be less than 3950 gallons?

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Answer:

0.6554 is the probability that the mean number of gallons of fuel needed to take off for a randomly selected sample of 40 jumbo jets will be less than 3950 gallons.                                  

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 4000 gallons

Standard Deviation, σ = 125 gallons

Sample size, n = 40

We are given that the distribution of amount of fuel is a bell shaped distribution that is a normal distribution.

Formula:

[tex]z_{score} = \displaystyle\frac{x-\mu}{\sigma}[/tex]

Central limit theorem:

As the sample size increases, the distribution of sample mean has a similar popular distribution shape.

P(sample of 40 jumbo jets will be less than 3950 gallons)

P(x < 3950)

[tex]P( x < 3950) = P( z < \displaystyle\frac{3950 - 4000}{125}) = P(z < -0.4)[/tex]

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

[tex]P(x < 3950) = 0.6554 = 65.54\%[/tex]

0.6554 is the probability that the mean number of gallons of fuel needed to take off for a randomly selected sample of 40 jumbo jets will be less than 3950 gallons.

The probability that the number of gallons of fuel needed to take off for a randomly selected sample of 40 jumbo jets will be less than 3950 gallons is 0.66.

it is given that

Mean μ= 4000 gallons

Standard deviation σ = 125 gallons

Number of trials x = 3950 gallons

What is the formula for a z-score?

Z-score = (x-μ)/σ

Z-score = (3950-4000)/125

Z-score = -0.4

So probbaility P(x<3950) = P(z<-0.4)

From the standard normal table,

P(x<3950) = 0.66

Therefore, the probability that the number of gallons of fuel needed to take off for a randomly selected sample of 40 jumbo jets will be less than 3950 gallons is 0.66.

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