Question

Ram is visiting a friend. Ram knows that his friend has 2 children and 1 of them is a boy. Assuming that a child is equally likely to be a boy or a girl, then the probability that the other child is a girl, is ______.

पर्याय

• `1/2`

• `1/3`

• `2/3`

• `7/10`

Answer 1

Ram is visiting a friend. Ram knows that his friend has 2 children and 1 of them is a boy. Assuming that a child is equally likely to be a boy or a girl, then the probability that the other child is a girl, is `underline(1/2)`.

Explanation:

Event that at least one of them is a boy → A, Event that other is girl → B,
So, required probability

P(B/A) = `("P"("B" ∩ "A"))/("P"("A"))`

Now, total cases are 3 (BG, BB, GG)

∴ `("P"("B" ∩ "A"))/("P"("A")) = (1/3)/(2/3) = 1/2`   ....[∵ B ∩ A = {BG} and A = {BG, BB}]