Based on their own blood types, a couple has a 0.75 probability of having a child with type A blood. If the couple has 4 children, what is the probability that they will have 2 children with type A blood?

Use the binomial probability formula for exactly 2 children with type A: choose which 2 of the 4 children have type A, then multiply by the probability of that outcome. This gives C(4,2) × (0.75)² × (0.25)² = 6 × 0.5625 × 0.0625 ≈ 0.21. The correct choice is 0.21.

AI-written and checked against the verified answer.