Find the cutoff level for the highest 15% in normal distribution, given the mean and standard deviation

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The cholesterol levels of adult American women are approximately normal with the mean of 188 mg/dl and a standard deviation of 24 mg/dl. a company wants to test a certain medication for women falling in the highest 15% of cholesterol readings. What is the lowest cholesterol reading a women might have and still be in the test group?

Never done these type of problems so it would like help on this one so I could do others.

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Consider:

Experiment: Randomly select one American woman

Random Variable $CL$: $C$holesterol $L$evel

Possible Values $CL$: [$0$ mg/dl, $400$ mg/dl]

Determine $cl$: $P$($CL \ge$ $cl$) $=$ $0.15$

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