a normal population has a mean 7 and standard deviation7 Wha

a normal population has a mean =7 and standard deviation=7

What proportion of the population is less than 19?

Solution

Normal Distribution
Mean ( u ) =7
Standard Deviation ( sd )=7
Normal Distribution = Z= X- u / sd ~ N(0,1)                  
P(X < 19) = (19-7)/7
= 12/7= 1.7143
= P ( Z <1.7143) From Standard Normal Table
= 0.9568 ~ 95.68%