Question 133353
An auto repair shop takes an average of 45 minutes to complete a repair job. The owner of the shop has determined the repair time has a standard deviation of 8 minutes.  A customer comes into the shop and states that she will return in 35 minutes -- at which time she must have the car ready to drive off.  Using the normal probability distribution, what is the probability the car will be repaired in 35 minutes or less?

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Find the z-score of 35.
z(35) = (35-45)/8 = -1.25
P(time < 35) = P(z<-1.25) = 0.1056
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Cheers,
Stan H.