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Re: George has a total of B books in his library, 25 of which are hardcove
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18 Jun 2016, 04:52
IMO E info given f | Nf |total HC|25|- PB|- |- A) f | Nf |total HC|25|- PB|14|- T |40|- Clearly not sufficient B) f | Nf |total HC|25|35|60 PB|--|- T |--|- Insufficient
A and B combined f | Nf |total HC|25|35|60 PB|15|??| T |40|??| Still value of nonfiction paper back is not known there not sufficient So E
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Re: George has a total of B books in his library, 25 of which are hardcove
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20 Aug 2016, 01:31
In this kind of DS questions are fiction/non-fiction and hardcover/paperback options exhaustive? If there is no note that he has only these kinds of books, we can't assume it, right?
Re: George has a total of B books in his library, 25 of which are hardcove
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20 Aug 2016, 01:53
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manlog wrote:
In this kind of DS questions are fiction/non-fiction and hardcover/paperback options exhaustive? If there is no note that he has only these kinds of books, we can't assume it, right?
We cannot assume that because each of the statements clearly stated " and the rest ", implying other options could not be assumed.
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Re: George has a total of B books in his library, 25 of which are hardcove
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29 Aug 2018, 01:56
Bunuel wrote:
George has a total of B books in his library, 25 of which are hardcover fiction books. What is the value of B?
(1) 40 of the B books are fiction and the rest are nonfiction (2) 60 of the B books are hardcovers and the rest are paperbacks
It also took very long for me. After giving a thought again, I realized that it can be solved very easily by a table format. fiction Non ------------------------------------------------------------ Hardcover 25 35 from 2nd = 60 ------------------------------------------------------------- Paper 15 PF x ----- no info ----------------------------------------------------------------- Total 40 from 1st
Re: George has a total of B books in his library, 25 of which are hardcove
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30 Aug 2018, 15:24
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I completely agree that this question can be answered efficiently using a matrix box approach, also known as the double matrix. The one thing I want to add to this discussion is to answer the question: How do we know that we can use a matrix box on this question?
Whenever we see that a group can be divided into 2 parts in 2 different ways, we can use a matrix box. In this case, George's books can be divided into fiction and nonfiction (1st way) and hardcover and paperback (2nd way). This tells us that we can use a matrix box.
I hope that this helps others to more quickly recognize that a matrix box or double matrix will be useful on questions like these. If you want more practice on recognizing and using matrix boxes, please visit the following link, where I have compiled a list of questions on which you can use matrix boxes:
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79% (01:52) correct 
