Question 742117
The service time of the first service of a BMW car is found to be normally distributed with a mean of 70 minutes and a standard deviation of 9 minutes. 
What is the minimum service time if the BMW dealer is willing to give a free service to the 3% of customers who waited the longest for their cars to be serviced?
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Find the z-value with a right tail of 3%.
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invNorm(0.97) = 1.8808
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Find the corresponding time value.
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x = z*s + u
x = 1.8808*9+70
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x = 86.93 minutes
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Cheers,
Stan H.