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Gmat Prep 2

by navalpike » Mon Aug 10, 2009 2:02 pm
At a certain store, each notepad costs X dollars and each marker costs Y dollars. If $10 is enough to buy 5 notepads and 3 markers, is $10 enough to buy 4 notepads and 4 markers instead?

1. Each notepad costs less than $1

2. $10 is enough to buy 11 notepads

OA is E

Please explain your answer. Thanks,

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by tohellandback » Mon Aug 10, 2009 10:05 pm
IMO E
because:

from the question
5X+3Y<=10

1)X<1
3y<=10-5X
3Y<=5
Y<=5/3
take numbers, X=1/2.Y=1/2
sufficient to buy 4 notepads and 4 markers
X=.9, Y=5/3- cannot buy 4 notebooks and 4 markers.
NOT SUFF

2)not sufficient , we need to know the price of markers

combined
from 2, 11X<=10
X<=10/11
same reasoning as given in A
not suff
The powers of two are bloody impolite!!