The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 88 inches, and a standard deviation of 10 inches. What is the likelihood that the mean annual precipitation during 25 randomly picked years will be less than 90.8 inches?

Question

Quizplus · Accepted Answer

The standard error of the mean is 10/sqrt(25) = 2. The z-score for 90.8 is (90.8-88)/2 = 1.4. Using the standard normal distribution table, the probability of a z-score less than 1.4 is approximately 0.9192.

The Annual Precipitation Amounts in a Certain Mountain Range Are