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by sanju09 » Sat Jun 19, 2010 4:08 am
In a bookshop, the sales of scientific books increased by 40 percent while the sales of engineering books decreased by 50 percent from 2001 to 2002. If R is the ratio of the number of scientific books to the number of engineering books in 2001 and r the same ratio in 2002, what is k if it is given by k = r/R?
(A) 0.2
(B) 0.8
(C) 1
(D) 1.25
(E) 2.8
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by mj78ind » Sat Jun 19, 2010 4:13 am
s/e=R where s = scientific, e = engineering

1.4s/.5e = r

(1.4/.5)R=r, r/R = 2.8

E
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by amising6 » Sat Jun 19, 2010 4:37 am
sanju09 wrote:In a bookshop, the sales of scientific books increased by 40 percent while the sales of engineering books decreased by 50 percent from 2001 to 2002. If R is the ratio of the number of scientific books to the number of engineering books in 2001 and r the same ratio in 2002, what is k if it is given by k = r/R?
(A) 0.2
(B) 0.8
(C) 1
(D) 1.25
(E) 2.8
2001
scientific book sales s
enigneering books sales E
R=s/E

2002
scientific book sales 1.4s(increased 40 %)
enigneering books sales 0.5 E (decreased by 50%)
r=1.4s/0.5E


k=r/R
k=1.4/0.5=2.8
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by GMATGuruNY » Sat Jun 19, 2010 1:39 pm
The question is asking for a ratio:

Whenever the answer choices are fractions, decimals or percents and the problem contains unknowns, you can plug in your own values for the unknowns.

In 2001, let's say we have 100 science books and 100 engineering books. Then R = 100/100 = 1.

In 2002 the 100 science books would increase by 40% to 140.
The 100 engineering books would decrease by 50% to 50.
So r = 140/50 = 14/5.

Thus r/R = (14/5)/1 = 2.8.

The correct answer is E.
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