Question 872514
this problem uses the normal distribution and z-table values to calculate probabilities
1) calculate z-value for Pr(X<10)
z-value = (10 - 14) / 3 = -4/3 = -1.33
consult z-table of negative values and
Pr(X<10) = 0.09
2) Pr(X>21) = 1 - Pr(X<21)
the z-value for Pr(X<21) is (21 -14) / 3 = 7/3 = 2.33
consult z-table for positive values
Pr(X>21) = 1 - 0.99 = 0.01