Answer:
The probability of both children being boys in a family with 2 children is
3
1
.
There are 3 possible outcomes for the gender of each child: boy, girl, or unknown. There are 2 children, so there are 3
2
=9 possible combinations of genders for the 2 children.
Of these 9 combinations, 3 of them have both children being boys: BB, BG, and GB. So the probability of both children being boys is
9
3
=
3
1
.
However, this is only the probability if we don't know the gender of the first child. If we know that the first child is a boy, then the probability of both children being boys is
2
1
. This is because there are only 2 possible outcomes for the gender of the second child: boy or girl. If the first child is a boy, then the second child must be a boy in order for both children to be boys. So the probability is
2
1
.
Explanation:
Let's use the following notation for the children:
B: Boy G: Girl
There are 4 possible combinations for a family with 2 children:
1. BB (Both children are boys)
2. BG (First child is a boy, second child is a girl)
3. GB (First child is a girl, second child is a boy)
4. GG (Both children are girls)
Since we know that at least one child is a boy, we can eliminate the 4th combination (GG) as it doesn't meet the condition. Now we have 3 possible combinations left:
1. BB
2. BG
3. GB
Now, to find the probability that both children are boys (BB) from the remaining combinations, we can calculate it as follows:
Probability = (Number of favorable outcomes) / (Total possible outcomes)
Probability = 1 (BB) / 3 (BB, BG, GB)
Probability = 1/3
So, the probability that both children are boys is 1/3.