The allele for the ability to roll one's tongue is dominant over the allele for the lack of this ability. in

Question

a population of 500 individuals, 25 percent show the recessive phenotype. how many individuals would you expect to be homozygous dominant and heterozygous for this trait?

Answer 1

This is easy.  25% would be homozygous dominant (125).  50% would be heterozygous (250).