Question

question
in a class of 23 students, 7 have a brother and 5 have a sister. there are 2 students who have a brother and a sister. what is the probability that a student who has a brother also has a sister?
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Explanation:

Step1: Identify relevant groups

We know 7 students have a brother, and 2 of those 7 also have a sister.

Step2: Apply conditional probability formula

The probability that a student with a brother also has a sister is the number of students with both a brother and a sister divided by the number of students with a brother. So we calculate $\frac{\text{Number of students with both}}{\text{Number of students with a brother}}=\frac{2}{7}$.

Answer:

$\frac{2}{7}$