Help, help, help! genetics?

Question

In a town, many people have a lethal gene causing clotting blood at birth. It is present in 1 out of 500 births. It kills ONLY when homozygous dominant. If population is 12,000 compute gene frequency for normal and for lethal.


I tried but got lost!

Answer 1

Hardy-Weinberg says p^2 + 2pq + q^2 = 1
q^2 = 1/500 = 0.002
q = 0.0447 = gene frequency of lethal allele
p+q=1
p+0.0447=1
p=0.9553 = gene frequency of normal