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If w, x and y are different positive integers

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by Vincen » Fri Sep 29, 2017 7:01 pm
If w, x and y are different positive integers, and wxy = 24, is xy divisible by 6?

(1) wy is not divisible by 6.

(2) x is even.

The OA is E.

How can I conclude that the correct option is E? Experts, could you help me?
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Source: — Data Sufficiency |

Answer

by [email protected] » Sat Sep 30, 2017 4:19 pm
Hi Vincen,

Certain Quant questions include 'restrictions' that limit the number of possible outcomes. In those situations, it can often be useful to list out all of the possibilities BEFORE you actually approach the rest of the prompt.

Here, we're told that W, X and Y are DIFFERENT positive integers and that (W)(X)(Y) = 24. Based on this information, these are the only possibilities:
1, 2 and 12
1, 3 and 8
1, 4 and 6
2, 2, and 6
2, 3 and 4

We're asked if (X)(Y) is divisible by 6. This is a YES/NO question.

1) (W)(Y) is NOT divisible by 6...

IF... W=1, Y=4, X=6 then the answer to the question is YES.
IF... W=3, Y=1, X=8 then the answer to the question is NO.
Fact 1 is INSUFFICIENT

2) X is EVEN.

We can use the same 'TESTs' from Fact 1 in Fact 2....
IF... W=1, Y=4, X=6 then the answer to the question is YES.
IF... W=3, Y=1, X=8 then the answer to the question is NO.
Fact 2 is INSUFFICIENT

Combined, we already have to different examples that 'fit' BOTH Facts and provide two different results (a "YES" and a "NO"), so there's no more work needed.
Combined, INSUFFICIENT

Final Answer: E

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
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