how much do 5 pencils cost?

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how much do 5 pencils cost?

by vittalgmat » Thu Jan 08, 2009 1:53 am
A stationery store sells pens and pencils. Provided that the price of each item is expressed as a whole number of cents, how much do 5 pencils cost?

1. 5 pencils and 3 pens cost 30 cents
2. 4 pencils and 4 pens cost 32 cents

[spoiler]OA: A
This is tricky!!!!. If u fell for C then u r not alone!!!!.:-)[/spoiler]
Source: — Data Sufficiency |

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by mental » Thu Jan 08, 2009 2:12 am
cost is in whole numbers is the key

st1: Let the cost of pencil be x and pens be y. Also as they do have some cost we eliminate (x or y = 0)

5x + 3y = 30
only integral solution to this equation is x=3, y=5
SUFFICIENT

st2: 4x + 4y = 32
x+y=8
(1,7); (2,6); etc. More than one solution. INSUFF