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Find Probability the Mean is the Given Number

You have graduated from college and have been working hard to get established in your field. You eventually land a perfect job where you make tons of money. You decide to step up from the 1992 Chevrolet Cavalier that you have been nurturing for a number of years into a more "comfortable" car (a.k.a. more expensive). You decide to give your nephew who just got his drivers license the Cavalier; however, it needs a little work. You do some research and find out that the mean amount of time it takes a mechanic to rebuild a Cavalier transmission is 8.4 hours and a standard deviation of 1.8 hours. Judy warned you in her statistics class that you would never be the same after taking that class. You find yourself thinking...If 40 mechanics are randomly selected, what is the probability that their mean rebuild time exceeds 8.1 hours?
a. 0.8531
b. 0.7285
c. 0.8457
d. 0.9146

Solution Preview

Mean = 8.4
SD = 1.8
N = 40
First, Standard error is SE = SD / ...

Solution Summary

This shows how to find the probability that the mean exceeds a given number.

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