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Problem 348

AMC 12 late, AIME early

Combinatorics Difficulty 4.8 Find the answer

A bag contains 15 balls. Exactly 3 of these balls are red. Alex reaches into the bag and randomly selects one of the balls. What is the probability that the ball that Alex selects is red?
(A) $\frac{1}{5}$
(B) $\frac{4}{5}$
(C) $\frac{1}{15}$
(D) $\frac{1}{4}$
(E) $\frac{14}{15}$

Your answer

Official solution

Since 3 of the 15 balls are red, then the probability that Alex randomly selects a red ball is $\frac{3}{15}$ or $\frac{1}{5}$ .

ANswer: (A)

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.