Question

In a hospital, 13 boys were born in succession before a girl was born. What is the probability that after 13 male births, the 14th child will be a boy?

Answer 1

The probability of birth of a girl child or a boy child is 50% or 0.5 in each time of birth as it is controlled by the Sex chromosomes.

The sex chromosomes are segregatted into gametes according to Mendel's law of segregation. The eggs always contain X chromosome and sperms may have either X or Y chromosome , Hence the probability of the fusion of a X chromosome bearing egg with Y chromosome of sperm is 50% and the probability of the fusion of a X chromosome bearing egg with a sperm having X chromosome is 50% irrespective of the succession of birth. So the the probability of 14th child wiil be a boy is 50% or 0.5.