7. [4pt] A study of the amount of time it takes a mechanic to rebuild the...

7. [4pt] A study of the amount of time it takes a mechanic to rebuild the transmission for a 2010 Chevrolet Colorado shows that the mean is 8.4 hours and the standard deviation is 1.8 hours.

a. If one person is randomly selected, find the probability that his/her rebuild time is less than 8.9 hours.

b. If 40 mechanics are randomly selected, find the probability that their mean rebuild time is less than 8.9 hours.

Solutions

Expert Solution

a).If one person is randomly selected, the probability that his/her rebuild time is less than 8.9 hours be:-

[ in any blank cell of excel type =NORMSDIST(0.2778) ]

b).sample size (n) =40

the sample mean will follow normal distribution with :-

the probability that their mean rebuild time is less than 8.9 hours be:-

[ in any blank cell of excel type =NORMSDIST(1.7569) ]

*** if you have any doubts about the problem please mention it in the comment box... if satisfied please LIKE.

orchestra answered 1 year ago

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