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# Twenty-five percent of all automobiles undergoing an emissions inspection at a certain inspection station fail the inspection.

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Twenty-five percent of all automobiles undergoing an emissions inspection at a certain inspection station fail the inspection.

(d) What is the probability that among 25 randomly selected cars, the number that pass is within 1 standard deviation of the mean value?

Guest Apr 11, 2017
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Twenty-five percent of all automobiles undergoing an emissions inspection at a certain inspection station fail the inspection.

(d) What is the probability that among 25 randomly selected cars, the number that pass is within 1 standard deviation of the mean value?

I think this is a trick question.....

The number that are within 1 standard deviation of the mean in a normal distribution, which I think is assumed here, is always  68%

Melody  Apr 11, 2017
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"Twenty-five percent of all automobiles undergoing an emissions inspection at a certain inspection station fail the inspection.

(d) What is the probability that among 25 randomly selected cars, the number that pass is within 1 standard deviation of the mean value?"

I've assumed a binomial distribution.  i.e. each car either passes or fails.

.

Alan  Apr 11, 2017