SOLUTION: the distribution of cholesterol levels in teenage boys is approximately normal with a mean of 170 and a standard deviation of 30. what is the minimum cholesterol level of the top
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Question 1085640: the distribution of cholesterol levels in teenage boys is approximately normal with a mean of 170 and a standard deviation of 30. what is the minimum cholesterol level of the top quintile (top fifth) of teenage boys to the nearest whole number?
I do not understand how to work this?
Thank you
Julia
You can put this solution on YOUR website! the top fifth is 80% to 100% since 5 * 20% = 100%
:
check the z-tables for the z-score associated with 80% ( minimum of the top fifth)
:
0.84 = (X - 170) / 30
:
X - 170 = 30 * 0.84
:
X = 170 + (30 * 0.84) = 195.2
:
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the minimum cholesterol level of the top quintile (top fifth)
of teenage boys is
:
195
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