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Number Properties... Can u solve it?

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Number Properties... Can u solve it?

by gokoli » Sat Aug 13, 2011 4:05 pm
If X and Y are greater than 0, is x=1?

(1) x/y = 1

(2) xy = 1

OA: C


I don't understand why it's C.

Shouldn't statement (2) be sufficient?

If xy=1 wouldn't that mean x and y are both "1" b/c given "x and y >0"?

What am I missing?
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by Tani » Sat Aug 13, 2011 5:11 pm
Given B, X could be 1/2 and y could be 2, or x could be 1/4 and y could be 4 , etc.

We are only told they are positive. We are not told that x and y are integers. On number properties problems, always watch for special cases such as fractions (especially those between one and zero), positives, negatives etc.
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by edvhou812 » Sat Aug 13, 2011 9:07 pm
The product of many number pairs can equal '1'. Best thing to do is to use algebra.

2) xy = 1; x = 1/y. Since we don't know 'y', there is no way for us to know if 1/10 of 'y' is greater than 1. (insufficient)

As you pointed out, x and y are both equal to '1', but there isn't any way to truly know that until we evaluate both statements.
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