Official Guide Explanation:
Data Sufficiency #77

Background

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Solution and Metadata

Question: 77
Page: 158
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Ratio and Proportion >
Category 2: Word Problems > Other >

Explanation: To determine how many of the leftover marbles are red, you need to know how many of the 9 removed marbles were red.

Statement (1) is sufficient: if the ratio of red marbles to blue marbles was 2:1, you can solve for how many of the 9 marbles were each color. Statement (2) is insufficient: you need to know how many of all 9 marbles were red; just because (2/3) of the first 6 marbles removed were red does not mean that (2/3) of the remaining marbles were red. Choice (A) is correct.

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