What is the probability that three are males and two are female? The human sex ratio at birth is commonly thought to be 107 boys to 100 girls. Suppose five infants are chosen at random. 
(A) What is the probability that three are males and two are female?
(B) What is the probability that at least one of them is a male?
My work: (A) $(5C2 * 5C3)$ / $207C5$
(B) $(5C1 * 202C)4$ / $207C5$
I'm not sure if these are correct.

Let $p=\mbox{probability for a boy}$ and $q=\mbox{probability for a girl}=1-p$. Then, we know $p+q=1$ and $\frac{p}{q}=\frac{107}{100}$. Thus, $p=0.516$ and $q=0.483$
Now, we have a binomial distribution $Bin(5,0.516)$
A) $\binom{5}{3}p^3q^2=0.320$
B) $P(\mbox{at least one boy})=1-P(\mbox{no boys})=1-\binom{5}{0}p^0q^5=1-0.026=0.973$
