Question

In a two children family, one child is a boy. What is the probability that the other child is a girl?
A) $\dfrac{1}{3}$
B) $\dfrac{1}{2}$
C) $\dfrac{2}{3}$
D) $\dfrac{1}{6}$

Answer 1

First, we will first use the formula of the probability of any event happening is given by dividing the number of outcomes of that event divided by the total number of events, that is; $P = \dfrac{{{\text{Number of outcomes}}}}{{{\text{Total number of outcomes}}}}$to find the required value.

Complete step by step solution:
We are given that in a two children family, one child is a boy.
We know that there is a total of 2 possibilities as it is either boy or a girl.
We know that the probability of any event happening is given by dividing the number of outcomes of that event divided by the total number of events, that is; $P = \dfrac{{{\text{Number of outcomes}}}}{{{\text{Total number of outcomes}}}}$.
Finding the probability of the chance of the second child be a girl, we get
$\Rightarrow P = \dfrac{1}{2}$

Hence, option B is correct.

Note:
In solving these types of questions, you should be familiar with the formula to find the probability of any event happening and not happening. Some students get confused while applying formulae. In this question, one needs to know that there are only two possibilities. This is a really simple problem, just a knowledge of probability will help us to find this answer.