Example 4
X = 10, SD = 2, X1 = 6.6, X2 = 13
n SD = 1                 
n             .3023            .4332
n  ___________________________________________
n-3           -2            -1           0           1          2           3     z-scores
n     
n
nX1 = 6.6, X2 = 13
nz = -.85, z = 1.5
np(6.6 < X < 13) = .7355