Question 418768: Carbon monoxide (CO) emissions for a certain kind of car vary with mean 2,9g/mi and standard deviation 0.4g/m. A company has 80 of these cars in its fleet. Let -y (the - is supposed to be over y) represent the mean CO level for the company's fleet.
a) What's the approximate model for the distribution of -y (the - is supposed to be over the y)? Explain.
b) Estimate the probability that -y (he - is supposed to be over the y) is between 3.0 and 3.1g/mi.
c) There is only a 5% chance that the fleet's mean CO level is greater what value?
THANKS
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Carbon monoxide (CO) emissions for a certain kind of car vary with mean 2,9g/mi and standard deviation 0.4g/m.
A company has 80 of these cars in its fleet.
Let -y (the - is supposed to be over y) represent the mean CO level for the company's fleet.
a) What's the approximate model for the distribution of -y (the - is supposed to be over the y)? Explain.
mean of y-bar = mean of y = 2.9g/mi
std of y-bar = 0.4/sqrt(80)
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b) Estimate the probability that -y (he - is supposed to be over the y) is between 3.0 and 3.1g/mi.
t(3) = (3-2.9)/[0.4/sqrt(80)] = 2.2361
t(3.1) = (3.1-2.9)/[0.4/sqrt(80)] = 4.4722
P(3<= y-bar <=3.1) = P(2.2361<= t <= 4.4722 when df = 79) = 0.0141
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c) There is only a 5% chance that the fleet's mean CO level is greater what value?
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Find the t-value with a right tail of 5% when df = 79
invT(0.95,79) = 1.6644
Find the corresponding y-bar value using y-bar = ts+u
y-bar = 1.6644+2.9 = 2.9744
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Cheers,
Stan H.
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