GMAT PREP Q, CHEEKY ONE

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GMAT PREP Q, CHEEKY ONE

by georgy » Thu Dec 18, 2008 3:59 am
!!THE DEVIL LIES IN (2)!!

CAN SOMEONE TELL WHY THE ANSWER TO THIS PREP Q IS CHOICE D, NOT A.

THE SUM OF POSITIVE INTEGERS X AND Y IS 77. WHAT IS THE VALUE OF XY?

(1) X = Y + 1
(2) X AND Y HAVE THE SAME TENS DIGIT
Source: — Data Sufficiency |

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by mals24 » Thu Dec 18, 2008 4:57 am
Youve figured out St 1 is SUFF

St 2: 77/2 = 38.5

So our possible combinations for X and Y can be (38, 39), (37, 40), (36,41) so on. Apart from 38,39 in all the other combinations the tenths value of X and Y will always differ. So since we can sufficiently find a unique combination for X and Y (38,39) St 2 is suff. Answer is D.
Last edited by mals24 on Thu Dec 18, 2008 5:38 am, edited 1 time in total.

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by iamcste » Thu Dec 18, 2008 5:33 am
mals24 wrote:So since we can sufficiently find a unique value for X and Y (38,39) .
Adding to mals 24,

Only combinations meeting criteria are (X,Y)- (38,39) or ( 39,38)

so, we cant find a unique value of X, Y as X could be 38/39 and Y could be 39/38 ( in either case sum is 77)

But, in any case the product XY ( Aim of the question) remains same

( 38*39 =39*38)

If question aimed only for X or Y, I am sure ans would have been A

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by ronniecoleman » Thu Dec 18, 2008 5:33 am
IMO D
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by mals24 » Thu Dec 18, 2008 5:37 am
woops sorry I meant you can find a unique combination for X and Y (38,39).

Thanks for pointing out the error iamcste.

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by iamcste » Thu Dec 18, 2008 5:39 am
mals24 wrote:woops sorry I meant you can find a unique combination for X and Y (38,39).

Thanks for pointing out the error iamcste.
No worries... :D

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by georgy » Thu Dec 18, 2008 9:14 am
iamcste wrote:
mals24 wrote:woops sorry I meant you can find a unique combination for X and Y (38,39).

Thanks for pointing out the error iamcste.
No worries... :D
thank u mals,cste,ron

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by rippersid » Tue Jan 06, 2009 8:12 am
How does
x and y have the same tens digit translate into "St 2: 77/2 = 38.5 "?

Any clarifications would be great :)
mals24 wrote:Youve figured out St 1 is SUFF

St 2: 77/2 = 38.5

So our possible combinations for X and Y can be (38, 39), (37, 40), (36,41) so on. Apart from 38,39 in all the other combinations the tenths value of X and Y will always differ. So since we can sufficiently find a unique combination for X and Y (38,39) St 2 is suff. Answer is D.