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 has a sister given that they do not have a brother?
the table has rows: has a brother, does not have a brother; columns: has a sister, does not have a sister. values: has a brother - has a sister: 12, does not have a sister: 3; does not have a brother - has a sister: 7, does not have a sister: 8

Explanation:

Step1: Identify the relevant group

We need the number of students who do not have a brother (the condition) and among them, the number who have a sister. From the table, students who do not have a brother: those with a sister are 7, those without are 8. So total with no brother: $7 + 8 = 15$.

Step2: Calculate the probability

Probability = (Number with sister and no brother) / (Total with no brother) = $\frac{7}{15}$.

Answer:

$\frac{7}{15}$