Question 116516: The accounting department @ Weston Materials, Inc. 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 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 g arages take 28.7 hours or less to erect?
d)Of the garages, 5 percent take how many hours or more to erect?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The accounting department @ Weston Materials, Inc. 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 and 34 hours to erect?
z(29) = (29-32)/2 = -1
z(34) = (34-32)/2 = 1
P(32
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b)What percent of the garages take between 29 hours and 34 hours to erect?
P(29
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c)What percent of the garages take 28.7 hours or less to erect?
Find the z-score of 28.7
z(28.7) = (28.7-32)/2 = -1.65
Find P(z < -1.65) = 0.0495
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d)Of the garages, 5 percent take how many hours or more to erect?
Find the z-value that has 0.05 of the population above it.
z = 1.6449
find the x-value associated with that z value:
1.6449 = (x-32)/2
x-32 = 3.2897
x = 35.2897
5% take 35.2897 or more hours to erect.
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Cheers,
Stan H.
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