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 has a dog also has a cat?
Has a cat Does not have a cat
Has a dog 7 10
Does not have a dog 2 9

Answer 1

We want P(cat | dog) = (number with both) / (number with dog) = 7 / (7+10) = 7/17 ≈ 0.4118 (about 41.18%).