Question

In a class of students, the following data table summarizes how many students have a cat or a dog. What is the probability that a student who does not have a cat has a dog?
Has a cat Does not have a cat
Has a dog 3 2
Does not have a dog 13 5

Answer 1

We want P(has a dog | does not have a cat) = (students who do not have a cat and have a dog) / (all students who do not have a cat) = 2 / (2+5) = 2/7 ≈ 0.2857 (about 28.6%).