Example 5
X = 10, SD = 2, X1 = 6.6, X2 = 13
n SD = 1                 
n                     .1915   .4738
n  ___________________________________________
n-3           -2            -1           0           1          2           3     z-scores
n     
n
nX1 = 11, X2 = 13.88
nz = .5, z = 1.94
np(11 > X < 13.88) = .2823