Question 1176919
n=30 p=0.5
mean is np=15
variance is np(1-p)=7.5
sd is sqrt (V)=2.74
need to get 18 or more right
z > (17..5-15)/2.74 or > 2.5/2.74 or 0.91
that probability is 0.1814, using the normal approximation
the exact value is 0.1808