Question

A man was born with six fingers on each hand and six toes on each foot. His wife and their son have a normal number of digits. Having extra digits is a dominant trait. The couple's second child has extra digits. What is the probability that their next (third) child will have extra digits?

1) 1/2
2) 1/16
3) 1/8
4) 3/4
5) 9/16

Answer 1

The probability that the couple's third child will have extra digits is 9/16.

Step-by-step explanation:

The probability that their next (third) child will have extra digits can be determined by applying the product rule and sum rule of probability.

Since having extra digits is a dominant trait, the probability of the third child having extra digits is equal to the probability of one parent passing on the gene for extra digits (3/4) multiplied by the probability of the other parent passing on the gene for extra digits (3/4).

This gives us a probability of (3/4) x (3/4) = 9/16.