A normal population has a mean $\mu = 27$ and standard deviation $\sigma = 9$ What proportion of the population is between 26 and 31 ?
A) 0.2138
B) 0.7862
C) 0.4562
D) 0.6700

Question

A normal population has a mean $\mu = 27$ and standard deviation $\sigma = 9$ What proportion of the population is between 26 and 31 ?
A)  0.2138 
B)  0.7862 
C)  0.4562 
D)  0.6700

Quizplus · Accepted Answer

To find the proportion of the population between 26 and 31, we calculate the z-scores for 26 and 31. The z-score for 26 is $(26-27)/9 = -0.1111$ and for 31 is $(31-27)/9 = 0.4444$. Using the standard normal distribution table, the area between these z-scores is approximately 0.2138.

A Normal Population Has a Mean μ=27\mu = 27μ=27 And Standard Deviation

A Normal Population Has a Mean $\mu = 27$ And Standard Deviation