In a population at hardy-weinberg equilibrium with two alleles, a and a, 264 of the 1200 individuals display the recessive trait (aa). what is the estimated frequency of the a allele?

If A is dominant allele and a is recessive allel, than aa is recesive homozygous with the frequency q2, AA is dominant homozygous with frequency p2 and Aa is heterozygous with frequency 2pq

If the population is in HW then, p+q=1

264/1200=0.22

q2=0.22, q=0.47 and p=1-0.47=0.53