IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability that a random sample of 20 people have a mean IQ score greater than 110? (Round to 4 decimal places)

Question

IQ scores are normally distributed with a mean of 100  and a standard deviation of 15. What is the probability that a random sample of 20 people have a mean IQ score greater than 110? (Round to 4 decimal places)

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 of that Z score.