SAT Probability and conditional probability Practice Question 4 (Medium)

Question bank / Probability and conditional probability

Math · Problem-Solving and Data AnalysisMedium

	Owns a dog	Does not own a dog	Total
House	42	28	70
Apartment	18	62	80
Total	60	90	150

The table summarizes the results of a survey of $150$ people about their housing type and whether they own a dog. If one person from the survey is selected at random, what is the probability that the person lives in a house and owns a dog?

$\frac{7}{25}$

$\frac{3}{5}$

$\frac{7}{10}$

$\frac{2}{5}$

Show answer and explanation

Answer: A

The number of people who both live in a house and own a dog is $42$ . Since the person is selected from all $150$ people, the probability is $\frac{42}{150} = \frac{7}{25}$ .

Choice B is $\frac{42}{70}$ , the probability that a house resident owns a dog; that conditions on living in a house rather than using all $150$ people.

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