Suppose that the blood cholesterol levels of all men aged 20 to 34 years follows the Normal distribution with mean µ=188 milligrams per deciliter (mg/dl) and standard deviation σ=41mg/dl. What standard deviation must x have so that 68% of all sample give an x within .75mg/dl of the mean?

How large of a SRS do you need to reduce the standard deviation of x to the value you found in (a)?