SAT Math Multiple Choice Practice Question 217: Answer and Explanation

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Question: 217

19. Anise has seven necklaces; two of them are identical. If she selects two necklaces without looking, what is the probability that she will select the identical necklaces?

A. 1/49
B. 1/42
C. 2/49
D. 1/21
E. 1/7

Correct Answer: D


D. When Anise picks out the first necklace, she has a 2/7 chance of picking one of the identical necklaces. (Recall that the probability of an event equals the number of ways for the event to occur divided by the total number of possible outcomes.) After she has picked the first identical necklace, she has a 1/6 chance of picking its mate. You want to use the counting principle to determine the probability of picking both necklaces: . (Check out Chapter 18 if you need to brush up on probability.)

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