An IQ test was administered to a random sample of 26 mental patients and the mean was found to be 99.7. For this test, the population values are known to be normally distributed and with a population standard deviation of 15. Construct a 90% confidence interval for the mean IQ of the population.

Question

An IQ test was administered to a random sample of 26 mental patients and the mean was found to be 99.7.  For this test, the population values are known to be normally distributed and with a population standard deviation of 15.  Construct a 90% confidence interval for the mean IQ of the population.

Damon · Answer

http://davidmlane.com/hyperstat/z_table.html