Final answer:
A couple with brown hair has a child with red hair and other children with brown hair. The genotypes of the parents are Bb. The chance that one of the brown-haired children is a carrier for the red allele is less than 50% but greater than zero.
Step-by-step explanation:
Based on the given information, a couple with brown hair has a child with red hair and children with brown hair. This suggests that the parents have the genotype Bb, where B represents the allele for brown hair and b represents the allele for red hair.
To determine the chance that one of the brown-haired children is a carrier for the red allele, we need to consider the possible genotypes of the children.
Since one of the parents has the genotype Bb, they can pass on either the B or b allele. Therefore, the possible genotypes for the brown-haired children are BB (brown hair, not a carrier) and Bb (brown hair, carrier).
The chance that one of the brown-haired children is a carrier for the red allele can be calculated by dividing the number of brown-haired children who are carriers (Bb) by the total number of brown-haired children (BB + Bb). Let's say there are x brown-haired children. So, the chance would be:
Chance = (Number of Bb genotype brown-haired children) / (Number of BB genotype brown-haired children + Number of Bb genotype brown-haired children)
Since the given information does not specify the number of children, we cannot provide an exact probability. However, we can say that the chance will be less than 50% but greater than zero, as at least one of the parents carries the red hair allele.