2013 AMC 8 Problem 14

Below is the video solution and professionally curated solution for Problem 14 of the 2013 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2013 AMC 8 solutions, or check the answer key.

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Concepts:basic probabilitycasework

Difficulty rating: 1140

14.

Abe holds 11 green and 11 red jelly bean in his hand. Bea holds 11 green, 11 yellow, and 22 red jelly beans in her hand. Each randomly picks a jelly bean to show the other. What is the probability that the colors match?

14\dfrac{1}{4}

13\dfrac{1}{3}

38\dfrac{3}{8}

12\frac{1}{2}

23\dfrac{2}{3}

Video solution:
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Written solution:

There are 24=82\cdot4=8 equally likely ways for Abe and Bea to choose their jelly beans. The colors match if they both choose green, which can happen in 11 way, or if they both choose red, which can happen in 12=21\cdot2=2 ways.

Thus 33 of the 88 outcomes match, for probability 38\dfrac{3}{8}.

Thus, C is the correct answer.

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