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by nafiul9090 » Fri Apr 08, 2011 8:36 pm
If x and y are nonnegative integers and x + y = 25, what is x?
(1) 20x + lOy < 300
(2) 20x + lOy> 280




statement 1
20x+10y<300
=2x+Y<30
=2x+y<25+5
=2x+y<x+y+5
=x<5
insufficient

statement 2
20x+10y>280
=2x+Y>28
=2x+y>25+3
=2x+y>x+y+3
=x>3
insufficient


together we get 3<x<5.so x must be 4

so answer is c

is my approach ok?
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Source: — Data Sufficiency |
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by vineeshp » Fri Apr 08, 2011 8:57 pm
Looks fine to me.

Is there an issue with the answer?
Vineesh,
Just telling you what I know and think. I am not the expert. :)
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by force5 » Mon Apr 11, 2011 11:32 am
yes looks good nafiul9090. Answer has to be C
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by Geva@EconomistGMAT » Mon Apr 11, 2011 11:50 pm
nafiul9090 wrote:If x and y are nonnegative integers and x + y = 25, what is x?
(1) 20x + lOy < 300
(2) 20x + lOy> 280




statement 1
20x+10y<300
=2x+Y<30
=2x+y<25+5
=2x+y<x+y+5
=x<5
insufficient

statement 2
20x+10y>280
=2x+Y>28
=2x+y>25+3
=2x+y>x+y+3
=x>3
insufficient


together we get 3<x<5.so x must be 4

so answer is c

is my approach ok?
It's good. Would just like to point out that you can also isolate (x+y) on the left side of the inequality and substitute that for 25, instead of isolating 25 on the right and substituting that for x+y.
For example:

Stat. (1)
20x+10y<300
=2x+Y<30
=x+x+y<30
=x+25<30
=x<5
Geva
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