Answer:
A So out of 4 people who have a sister, 1 has a brother.
Step-by-step explanation:
P(B|A)
Given That event A has occurred, or the person has a sister.
This means we are now in the red circle
The probability of event B happening is .25
Event B is that the person has a brother
In English
Given that the person has a sister, the probability the person has a brother is 1/4
So out of 4 people who have a sister, 1 has a brother.
