Question 694408: a corporation's fleet of cars has an annual operating cost of $100,000. suppose the operating cost are normally distributed with a standard deviation of 100.
a. what is the operating cost below which only 25% of the operating cost lies?
b. what is the operating cost above which 55% of the operating costs lie?
c. what is the operating cost would be more than 75% of operating cost?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! a corporation's fleet of cars has an annual operating cost of $100,000. suppose the operating cost are normally distributed with a standard deviation of 100.
a. what is the operating cost below which only 25% of the operating cost lies?
Find the z-value with a left tail of 0.25:: invNorm(0.25) = -0.6745
Solve for cost using x = z*s+u
x = -0.6745*100+100,000
x = $99932.55
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b. what is the operating cost above which 55% of the operating costs lie?
Find the z-value with a left tail of 0.45:: invNorm(0.45) = -0.1257
x = -0.1257*100+100,000
x = $99987.43
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c. what is the operating cost would be more than 75% of operating cost?
I'll leave that to you.
Cheers,
Stan H.
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