math
posted by Belinda on .
In a large population of adults, the mean IQ is 112 with a standard deviation of 20. Suppose 200 adults are randomly selected for a market research campaign. The probability that the sample mean IQ is greater than 110 is...?

your z score is (110112)/20 = .1
if you have a normal distribution table, look up the probability for that score, you should get .4602
that means the the prob. of a score of less than 110 is .4602
so the prob of getting higher than 110 is 1.4602
= .5398
here is a nice applet that lets you enter your original values, it graphs it and gives you the results
http://davidmlane.com/hyperstat/z_table.html