Official Guide Explanation:
Problem Solving #D14

Background

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Solution and Metadata

Question: D14
Page: 22
Difficulty: 7 (Very Difficult)
Category 1: Arithmetic > Sets > 2 sets
Category 2: Word Problems > Sets >

Explanation: This question is very similar to \#6 in the diagnostic. We can use the overlapping sets formula to handle it:

T = G1+ G2 - B + N

84 = 35 + G2 - 11 + N

We know that the number who volunteered to bring refreshments is 1.5x as many as those who volunteered to do neither, so G2 = 1.5N:

84 = 35+ 1.5N - 11+ N

84 - 35 + 11 = 2.5N

60 = 2.5N

N = 24

We're looking for G2, which is 1.5N = 1.5(24) = 36, choice (B).

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