Refer to “Medium or Large Drink? Describing the sampling distribution of x−
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1 −
x−
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2,” pp. 639–39]

The level of cholesterol in the blood for all men aged 20 to 34 follows a Normal distribution with mean 188 milligrams per deciliter (mg/dl) and standard deviation 41 mg/dl. For 14-year-old boys, blood cholesterol levels follow a Normal distribution with mean 170 mg/dl and standard deviation 30 mg/dl. Suppose we select independent SRSs of 25 men aged 20 to 34 and 36 boys aged 14 and calculate the sample mean cholesterol levels
x−
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M and
x−
x-

B. What is the shape, mean, and standard deviation of the sampling distribution of
x−
x-

M –
x−
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B?