Question

in a class of students, the following data table summarizes how many students have a brother or a sister. what is the probability that a student who has a brother also has a sister?

	has a brother	does not have a brother
does not have a sister	3	10

Explanation:

Step1: Identify relevant counts

Number of students with a brother: $2 + 3 = 5$
Number with both brother and sister: $2$

Step2: Calculate conditional probability

Probability = $\frac{\text{Both brother and sister}}{\text{Has a brother}} = \frac{2}{5}$

Answer:

$\frac{2}{5}$