Question

Solve the problem. Use the Central Limit Theorem. The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 109.0 inches, and a standard deviation of 10 inches. What is the probability that the mean annual precipitation during 25 randomly picked years will be less than 111.8 inches

Answer 1

0.91924

Explanation:

Given that :

A normal distribution has ;

Mean (m) = 109.0 inches

Standard deviation (σ) = 10 inches

Sample size (n) = 25

Probability that randomly picked years is less than 111.8 inches

Using the Zscore relation :

Zscore = (x - m) / (σ/√n)

x = score = 111.8 inches

Zscore = (111.8 - 109.0) / (10/√25)

Zscore = (2.8) / (10/5)

Zscore = 2.8 / 2

Zscore = 1.4

P(Z < 1.4) = 0.91924 ( using z probability calculator)

P(Z < 1.4) = 0.91924