Question 1091257
at least 50 would be 50 upward
the mean is np=75*0.80=60
the variance is np(1-p)=60*0.2=12
the sd is sqrt (12)=3.464
use continuity correction factor of 49.5
(49.5-60)/3.464=-3.03
This is the probability z >=-3.03, which is 0.9976
Exactly 50 is 75C50(0.8)^50*0.2^25=0.0025