Suppose that, in fact, the blood cholesterol level of all men aged 20 to 34 follows the normal distribution with mean of u = 188 milligrams per deciliter (mg/dl) and standard deviation = 41 mg/dl.

Question

Suppose that, in fact, the blood cholesterol level of all men aged 20 to 34 follows the normal distribution with mean of u = 188 milligrams per deciliter (mg/dl) and standard deviation = 41 mg/dl.
1.	Choose an SRS of 100 men from this population. What is the sampling distribution of x?  What is the probability that x takes a value between 185 and 191 mg/dl?  This is the probability that x estimates u within ± 3 mg/dl.
2.	Choose an SRS of 1000 men from this population.  Now what is the probability that x falls within ± 3 mg/dl of u?  The larger sample is much more likely to give an accurate estimate of u.

PsyDAG · Answer

Z = (score-mean)/SEm SEm = SD/√n Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z scores.