In a certain flock of sheep 91% of the sheep have white wool while the rest have black wool. Assume the population is in Hardy-Weinberg equilibrium. If black wool is a recessive trait, what percentage of the population is heterozygous for this trait?

Using the hardy-weinburg equation; 2p2 + 2pq + q2 = 1

2p2+2pq = 91% = 0.91

q2 = 9% = 0.09

Therefore q = 0.3; and since p + q = 1; then p = 1 - 0.3 = 0.7

P = 0.7

Heterozygous indivisuals in the population (i. e 2pq) therefore is derived as following;

2pq = 2 * 0.7 * 0.3 = 0.42 = 42%

The answer is 42%