bilibili Posted March 4, 2017 Share Posted March 4, 2017 (edited) On Monday, a class has 8 girls and 20 boys. On Tuesday, a certain number of girls joined the class just as twice that number of boys left the class, changing the ratio of girls to boys to 7 to 4. How many boys left the class on Tuesday? (A) 5 (B) 6 (C) 11 (D) 12 (E) 18 From Manhattan prep. Question, which # is bigger? number of boys left the class or number of girls joined the class?? Thx Edited March 4, 2017 by bilibili Link to comment Share on other sites More sharing options...

Black Beauty Posted March 5, 2017 Share Posted March 5, 2017 @bilibili The number of boys who left the class (12 boys) would be bigger since twice as many boys left than girls who joined. Link to comment Share on other sites More sharing options...

GREMasterEMPOWERRichC Posted March 13, 2017 Share Posted March 13, 2017 Hi bilibili, This question can be solved in a number of different ways - including TESTing THE ANSWERS. We know that there are 8 girls and 20 boys to start, and a certain number of girls joined and TWICE as many boys left the class (leaving us with a ratio of 7 girls for every 4 boys). We're asked for the number of boys that LEFT the class. To start, since the number of boys who left is TWICE the number of girls who joined, the number of boys who left MUST be an EVEN number (so we can eliminate Answers A and C immediately). Let's TEST Answer D: 12 boys IF... 12 boys left and 6 girls joined, we would have.... 8 + 6 = 14 girls 20 - 12 = 8 boys 14:8 = 7:4 This is an exact match for what we were told, so this MUST be the answer. Final Answer: D GRE Masters aren't born, they're made, Rich Link to comment Share on other sites More sharing options...

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