assume that adults have IQ scores that are normally distributed with a mean of 100 and a standard deviation of 20. find the probability that a randomly selected adult has an IQ less than 20.
2 answers
http://www.iqcomparisonsite.com/IQBasics.aspx
Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z score.