# Chi-squared test for HW equilibrium

The MN blood group in humans is under the control of a pair of codominant alleles, LM

and LN. In a group of 556 individuals, the following genotypic frequencies are found:

167 MM

280 MN

109 NN

(a) Calculate the frequency of the LM and LN alleles.

(b) Test (using the Chi-squared test) whether the genotype frequencies conform to the

Hardy-Weinberg distribution.

Genotypes

MM MN NN Sum

Observed number

Observed frequency

Expect frequency

Expected number

(O-E)2/E

https://brainmass.com/biology/genetics/chi-squared-test-for-hw-equilibrium-563575

#### Solution Preview

1. MM=p2=167/556=.30

MN=2pq=280/556=.50Next

NN=q2=109/556=.20

First determine the frequency of M using the following equation: p2+1/2(2pq). Substitute the numbers from each of the above observed values and solve for p.

.30=1/2(.50) =.55 therefore P=.55

1-.55=.45

To get pq simply multiply the above values. To get 2 pq multiply pq by 2.

pq= .55x.45=.2475

2pq=.2475x2=.495

p2=.3025

q2=.2025

These solutions are the expected frequencies for the alleles if the population ...

#### Solution Summary

This solution will explain how to use a chi-squared test to determine whether or not the blood groups of a population are in Hardy-Weinberg equilibrium. A link to a similiar example problem is included.