Answer:
A quarter (25%) of the individuals that carry at least one s allele are homozygotes.
Explanation:
Knowing the frequency of s, we can find the frequency of both alleles, because:
Now, if the population of guppies is at Hardy-Weinberg equilibrium, we can find how many heterozygotes and homozygotes are, like this:
We know that:
So, we need to know what is the frequency of guppies Ss (2pq) and ss (s2):
Finally, to find the fraction of homozygotes (ss) of the individuals that carry at least one s allele, we need to divide the frecuency of homozygotes ss into the frequency of heterozygotes Ss:
0.25 or 25% of the guppies carring the allele s are homozygotes.