Question

In 2014, new cars had an average fuel efficiency of 27.9 miles per gallon with a standard deviation of 6.8 miles per gallon. a sample of 30 new cars is taken. [6 points] a) what is the probability the sample has a mean gas mileage between 27 and 29 miles per gallon?

Answer 1

The probability of the sample having a mean gas mileage between 27 and 29 miles per gallon will be 0.0116.

What is a normal distribution?

The Gaussian Distribution is another name for it. The most significant continuous probability distribution is this one. Because the curve resembles a bell, it is also known as a bell curve.

The z-score is a statistical evaluation of a value's correlation to the mean of a collection of values, expressed in terms of standard deviation.

In 2014, new cars had an average fuel efficiency of 27.9 miles per gallon with a standard deviation of 6.8 miles per gallon. a sample of 30 new cars is taken.

Then the probability the sample has a mean gas mileage between 27 and 29 miles per gallon will be

The value of the z-score at x = 27, we have

$z = \dfrac{27 - 27.9}{6.8}\\\\z = -0.13$

The value of the z-score at x = 29, we have

$z = \dfrac{29 - 27.9}{6.8}\\\\z = 0.16$

Then the probability will be

$\begin{aligned} P(-0.13 < z < 0.16 ) &= P (z < 0.16) - P(z > -0.13) \\\\&= P (z < 0.16) - [ 1 - P(z < -0.13) ]\\\\&= 0.56425 - (1 -0.44735)\\\\&= 0.0116 \end$

More about the normal distribution link is given below.

https://brainly.com/question/12421652

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