In: Statistics and Probability
Solve the problem. The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 107 inches, and a standard deviation of 12 inches. What is the probability that the mean annual precipitation during 36 randomly picked years will be less than 109.8 inches?
A. 0.9192
B. 0.4192
C. 0.5808
D. 0.0808
Solution :
Given that ,
mean = = 107
standard deviation = = 12
n = 36
= 107 and
= / n = 12 / 36 = 12 / 6 = 2
P( < 109.8) = P(( - ) / < (109.8 - 107) / 2) = P(z < 1.4)
Using standard normal table,
P( < 109.8) = 0.9192
Probability = 0.9192
Option A) is correct .