Assume that the probability is 1/2 that a baby born is a boy. If a couple has two children, what is the probability that both are girls? Assume that births are independent of each other.
Pr(girl, girl)= 1/2 * 1/2
.25
3/4
To calculate the probability that both children are girls, we need to consider all the possible outcomes.
When a couple has two children, the possible outcomes are: (1) boy-boy, (2) boy-girl, (3) girl-boy, and (4) girl-girl.
We are interested in the probability of outcome (4) - having both children be girls.
Given that the probability of having a boy or a girl is 1/2, or 50%, we can assign a probability of 1/2 to each outcome (assuming independent births).
Since there are four possible outcomes, each with a 1/4 chance of occurring, the probability that both children are girls is 1/4.
So, the probability that a couple has two girls is 1/4 or 25%.