hardy weinberg?

Question

in a certain population the dominant phenotype of a certain trait occurs 91% of the time. what is the freqency of the dominant allele?

Answer 1

p^2+2pq+q^2=1
p^2 and 2pq are both dominant phenotypes

.91+q^2=1
q^2=.9
q=.3

and p+q=1, so p=.7

so .7 is the frequency of the dominant allele

Answer 2

p(p) + 2(p)(q) + q(q) = 1

where p is the frequency of the dominant allele and q is the freqency of the recessive allele.

0.91 = p(p) + 2(p)(q)


I'll let you figure out the rest, I don't want to do all your homework for you ;)