In a study of human blood groups, it was found that among a population of 400 individuals,230 were Rh + and 170 were Rh -. Assuming that this trait...

In a study of human blood groups, it was found that among a population of 400 individuals,230 were Rh+ and 170 were Rh-.. Assuming that this trait (i.e., being Rh+) is controlled by a dominant allele (D), calculate the allele frequencies of D and d. How many of the Rh+ individuals would be expected to be heterozygous?