statistics
posted by jc .
a random sample of 100 college students is taken from the student body of a large university. assume that a population mean of 20 hours and a population standard deviation of 15 hours describes the weekly study estimates for the entire student body. About 68 percent of the sample means in this sampling distribution should be between?

68% are approximately within mean ± 1 SD
Z = ±1 = (score  mean)/SEm
SEm = SD/√(n1) = approx. SD/10
Insert values in above Z equation to get scores. 
consider a normal distribution with mean 27 and standard deviation 6. What is the probability a value selected at random from this distribution is great than 27?