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For every novel in the school library there are 2 science books; for

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For every novel in the school library there are 2 science books; for [#permalink]

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22 Oct 2017, 05:10
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Difficulty:

25% (medium)

Question Stats:

88% (00:45) correct 12% (00:25) wrong based on 75 sessions

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For every novel in the school library there are 2 science books; for each science book there are 7 economics books. Express the ratio of economics books to science books to novels in the school library as a triple ratio.

(A) 7 : 2 : 1
(B) 7 : 1 : 2
(C) 14 : 7 : 2
(D) 14 : 2 : 1
(E) 14 : 2 : 7
[Reveal] Spoiler: OA

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Re: For every novel in the school library there are 2 science books; for [#permalink]

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22 Oct 2017, 06:12
Bunuel wrote:
For every novel in the school library there are 2 science books; for each science book there are 7 economics books. Express the ratio of economics books to science books to novels in the school library as a triple ratio.

(A) 7 : 2 : 1
(B) 7 : 1 : 2
(C) 14 : 7 : 2
(D) 14 : 2 : 1
(E) 14 : 2 : 7

$$S=2N => S:N=2:1$$

$$E=7S => E:S=7:1$$ or $$E:S=14:2$$ (to make $$S$$ equivalent to $$2$$ to compare it with the ratio $$S:N$$)

So $$E:S:N = 14:2:1$$

Option D

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Re: For every novel in the school library there are 2 science books; for [#permalink]

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22 Oct 2017, 06:31
Lets shorten everything
Science books: S
Novels: N
Economics: E

From the question
N:S = 1:2
S:E = 1:7

E:S:N?
If there is one N, 2 S are there too
So for 2 S, 14 E are there.
So
Ans: 14:2:1 (D)
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Re: For every novel in the school library there are 2 science books; for [#permalink]

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24 Oct 2017, 05:47
Bunuel wrote:
For every novel in the school library there are 2 science books; for each science book there are 7 economics books. Express the ratio of economics books to science books to novels in the school library as a triple ratio.

(A) 7 : 2 : 1
(B) 7 : 1 : 2
(C) 14 : 7 : 2
(D) 14 : 2 : 1
(E) 14 : 2 : 7

N:S=1:2
S:E=1:7 -> S:E=2:14 (in that way we obtain a mutual term and we can join the two ratio)
E:S:N=14:2:1

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Re: For every novel in the school library there are 2 science books; for [#permalink]

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25 Oct 2017, 12:11
First, I tried to figure out what the equation is.

E:S:N
Given there will be 14 econ books for every novel, I figured the ratio had to start and end with 14 and 1. Given that there are 7 econ books for every science book, I figured S=2.
14:2:1
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Re: For every novel in the school library there are 2 science books; for [#permalink]

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26 Oct 2017, 14:35
Bunuel wrote:
For every novel in the school library there are 2 science books; for each science book there are 7 economics books. Express the ratio of economics books to science books to novels in the school library as a triple ratio.

(A) 7 : 2 : 1
(B) 7 : 1 : 2
(C) 14 : 7 : 2
(D) 14 : 2 : 1
(E) 14 : 2 : 7

The ratio of novels to science books = 1 : 2

The ratio of science books to economics books is 1 : 7 = 2 : 14

So, the ratio of economics books to science books to novels = 14 : 2 : 1

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Jeffery Miller

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Re: For every novel in the school library there are 2 science books; for   [#permalink] 26 Oct 2017, 14:35
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