Question 304668
Among coffee drink men drink a mean of 3.2 cups per day w/a standard devivation of 0.8 cups. 
assume the number of coffee drink per day follow normal distribution 
a. what is proportion drink 2 cups per day or more?
Find the z-value of 2
z(2) = (2-3.2)/0.8 = -1.5
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P(x >=-2) = P(z >=-1.5) = 0.9332
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b. what is proportion drink no more than 4 cups per day?
Find the z-value of 4
z(4) = (4-3.2)/0.8 = 1
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P(x<4) = P(z<1) = 0.8413
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c. if the top 5% of coffee drinkers are considered heavy coffee drinkers, what is the minimum number of cups consumed by a heavy coffee drinker?
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Find the z-value that has a 5% right tail.
z = 1.645
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Find # of cups corresponding to that z-value:
x = zs+u
x = 1.645*0.8+3.2
x = 4.52 cups
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Cheers,
Stan H.
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