(1) Suppose IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability a random sample of 1200 people has a mean IQ of less than 99?
Suppose IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability a random sample of 150 people has a mean IQ between 102 and 103?
Suppose IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability a random sample of 100 people has a mean IQ of more than 104?