In a population of 1000 lemmings there are two alleles for skin colour, the dominant colour being cream (C) and the recessive being white (c). 350 individuals have white skin. Use Hardy-Weinberg to predict the number of homozygous recessive individuals.

Hardy-Weinberg Principle states that in a population of randomly mating individuals:
p + q = 1
p²+2pq+q²=1
White fur = homozygous recessive = q² = 350/100 = 0.35
Therefore q = sqrt(0.35)=0.59 (2sf)p = 1-0.59 = 0.41 (2sf)
Homozygous dominant = p² = (0.41)2 = 0.1668
No. homozygous dominant lemmings = 0.1668 x 1000 = 167 lemmings