Question

In a class of students, the following data table summarizes how many students have aаbrother or a sister. What is the probability that a student who has a brother also has aаsister?Has a brother Does not have a brotheraHas a sister42Does not have a sister318

Answer 1

For this case we have the following table:

Has a brother Not a brother

Has a sister 4 2

Not have a sister 3 18

We want the probability that a student who has a brother also has а sister, and we can do this:

4/7