Answer:
The frequency of the dominant A allele is 0,4 or 40%.
Explanation:
In this population, we have:
- "A" red body color Dominant
- "a" yellow doy color Recessive
So, individuals AA and Aa will be red and trouts aa will be yellow. In this case, 64% of the fish are red, so they are AA or Aa.
If the population is in Hardy-Weinberg equilibrium the following will be true:

Where:
frequency of AA
frequency of Aa
frequency of aa
It is known that 64% of population is red, in other words:

Or AA+Aa=0,64
So, it is possible to find the value of
(aa):




Now, there are two alleles in this population, therefore their frequencies will be:

So, from
it is possible to find q and p:



And:
