some families have an only child others choose to have two. Помогите написать сочинение по английскому по…

In a two-child family, one child is a boy. What is the probability that the other child is a girl? The 'one child is a boy' is ambiguous because it doesn't explicity explain that the other case 'one child is a girl' is being excluded.For instance if a parent of a two-child family walks into a room accompanied with a boy (one of their children) is the probability that the other child is a boy or girl anything but 50/50? The answer is NO.If I have a room full of parents of 2 children families (randomly selected) and I ask all those with a boy (implying 1 or more) to step forward — THEN and only then have I skewed the odds that for the parents that have stepped forward to 1/3 2/3.Again this is a very subtle point, and worth making explicitly. The fact to are making a decision is very important in this problem.This example from rec.puzzles.faq makes the 'question step' explicit