# Z Values and Garage Building Rate

The accounting department at Weston Materials, Inc., a national manufacturer of unattached garages, reports that it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours to erect the Red Barn model. Assume the assembly times follow

the normal distribution.

a. Determine the z values for 29 and 34 hours. What percent of the garages take between 32 hours and 34 hours to erect?

b. What percent of the garages take between 29 hours and 34 hours to erect?

c. What percent of the garages take 28.7 hours or less to erect?

d. Of the garages, 5 percent take how many hours or more to erect?

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#### Solution Preview

a. Determine the z values for 29 and 34 hours. What percent of the garages take between 32 hours and 34 hours to erect?

Given the mean mu=32 and standard deviation sigma=2.

For 29 hours, the z-value is equal to

(29-mu)/sigma=(29-32)/2=-1.5;

For 34 hours, the z-value is equal to

...

#### Solution Summary

167 words of explained calculations show how to find the z values for garage building rate as well as various percentage probabilities.