# How to solve this genetics exercise?

In a population in balance people with MN genotype are 3 times more than those with group NN. Find frequency p(LM) and q(LN)

### 1 Answer

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- hcbiochemLv 74 weeks ago
Let frequency of NN = x, and frequency of MN = 3x.

From the Hardy-Weinberg equation,

x = q^2 and

3x = 2pq

Also, you know that p = 1-q, so 3q^2 = 2(1-q)q

Factoring out q gives: 3q = 2-2q

5q = 2

q = 0.4

p = 1-q = 0.6

So, the frequency of LM (p) = 0.6 and frequency of LN(q) = 0.4

This all works since q^2 = 0.16 and 2pq = 2(0.6)(0.4) = 0.48 = 3x.

There may well be a different way to get to this answer, but this is how I saw it.

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