The mean of a binomial distribution is 20, and the standard deviation is 4. Calculate n, p, and q with usual notations.
(a) n=5,p=0.4,q=0.6
(b) n=25,p=0.8,q=0.2
(c) n=100,p=0.2,q=0.8
(d) n=400,p=0.05,q=0.95