hardy-weinberg HELP

[karenkay]

Hello,

I am having trouble understanding how to use the hardy-weinberg equilibrium equation.

I understand that the allelic frequencies must always add to 100% (i.e. p+q = 1) but I don't understand how to do a few questions.

If AA = 0.50, Aa = 0.25 and aa = 0.25, what are p and q? Is this population in equilibrium? The answer key says that p = 0.625 and q = 0.375. How is this?

I am working through this worksheet: (in particular #3)
http://life.bio.sunysb.edu/bio350/Answerkey.htm

[AstusAleator]

AA = .5
Aa = .25 (A = .125, a = .125)
aa = .25

p = AA + A = .5 + .125 = .625
q = a + aa = .25 + .125 = .375