a set of data is normally distributed with a mean of 28 and a standard deviation of 2. what percent of the data is between 23 and 31?

Question

Z score problem i don't know how to solve

Answer 1

P ( 23 <X < 31) = P ( (23-28)/2 < z < (31-28)/2)

 

                        = P ( -5/2 < z < 3/2)

 

                        = P(z<3/2) - P(z< -5/2)

 

                         = 0.9332 - 0.0062 

 

                         = 0.927