In the U.S. 42% of the population has type A blood. Consider taking a sample size 4. Let y denote the number of persons in the sample with type A blood.

a)Pr(y=O)
b)Pr(y=1)
C)Pr(y=2)

p(A) = .42

1-p(A) = .58
n = 4
for n = 4, binomial coefs are
1 4 6 4 1

P(y=0) = 1*.42^0*.58^4
P(y=1) = 4*.42^1*.58^3
P(y=2) = 6*.42^2*.58^2