A standard IQ test has a mean of 98 and a standard deviation of 16. We want to be 90% certain that we are within 8 IQ points of the true mean. Determine the sample size.

Question

stucci · Answer

(z * sigma / error )^2 round up

terry · Answer

assuming that adults have IQ scores that are normally distributed with a mean of 100 and standard deviation of 15. Find the probability that a randomly selected adult has an IQ less than 121.