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by grandh01 » Tue Sep 04, 2012 10:57 pm
Product of xy>27?

1) 2<x<5
2)6>y
[spoiler]
OA is E
I thought the answer was C, because used together we can say no xy is not greater than 27[/spoiler]
Source: — Data Sufficiency |

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by Anurag@Gurome » Tue Sep 04, 2012 11:04 pm
grandh01 wrote:Product of xy>27?

1) 2<x<5
2)6>y
[spoiler]
OA is E
I thought the answer was C, because used together we can say no xy is not greater than 27[/spoiler]
(1) 2 < x < 5 but we have no info about y; NOT sufficient.

(1) 6 > y but no info on x; NOT sufficient.

Combining (1) and (2), 2 < x < 5 and y < 6
If x = 3, y = 1, then xy = 3. Here xy < 27
If x = 4.9, y = 5.9, then xy = 28.9 > 27
No definite answer; NOT sufficient.

The correct answer is E.
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by alex.gellatly » Wed Sep 05, 2012 6:33 pm
grandh01 wrote: I thought the answer was C, because used together we can say no xy is not greater than 27
If x and y were integers this would be the case. You have to remember that the GMAT likes to trick us for things like this. Whenever you see a question like this make sure you know if they are integers or not. The GMAT will makes this very clear. If they are not integers be very careful!
A useful website I found that has every quant OG video explanation:

https://www.beatthegmat.com/useful-websi ... tml#475231

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by Brent@GMATPrepNow » Thu Sep 06, 2012 8:32 am
alex.gellatly wrote: You have to remember that the GMAT likes to trick us for things like this. Whenever you see a question like this make sure you know if they are integers or not. The GMAT will makes this very clear. If they are not integers be very careful!
Well said Alex! The question illustrates a common trap on the GMAT.

This is trap (along with others) is covered in our free video: https://www.gmatprepnow.com/module/gmat- ... cy?id=1105

Also, videos #11 and #12 (on the same page) cover additional myths and common traps related to Data Sufficiency questions.

Cheers,
Brent
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by alex.gellatly » Thu Sep 06, 2012 5:59 pm
Thanks Brent for the free vids!
A useful website I found that has every quant OG video explanation:

https://www.beatthegmat.com/useful-websi ... tml#475231