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OG quant review inequality problem

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OG quant review inequality problem

by manjus_mailme » Fri Jul 09, 2010 10:45 am
[y] denotes the greatest integer less than or equal to y.Is d < 1?

1) d= y-[y]
2) [d] =0

I could not understand the explanation for this problem.Very confusing.Can anybody pls tell me a simple approach to this problem.

I tried this problem in the following manner.

Assuming y=4
The greatest integer less than y is 3 and the greatest integer equal to y is 4.

1) d=4 - 3 or d= 4 -4
So d may be or may not be less than 1
Insufficient.

2) [d] =0 ,so d=0
sufficient.

Whats wrong with my approach ?The correct answer is D.
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by 4GMAT_Mumbai » Fri Jul 09, 2010 10:55 am
Hi,
Assuming y=4
The greatest integer less than y is 3 and the greatest integer equal to y is 4.
I am afraid this may not be right. The greatest integer lesser than or equal to 4 is 4.

hence, if y = 4; [y] = 4. hence, y-[y] = 0

If d = y-[y], then d is less than 1 indeed. Hence, sufficient.

In fact 0 <= d < 1.

Stmt 2:

[d] = 0 need not mean that d is only 0. d could be 0.1 or 0.2 or 0.9999999999999 or 0.111111111111.

But, it does mean that d < 1. Hence, sufficient.

Hence, D. Hope this helps. Thanks.
Naveenan Ramachandran
4GMAT, Dadar(W) & Ghatkopar(W), Mumbai
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by manjus_mailme » Fri Jul 09, 2010 11:14 am
It was really helpful.Thanks

4GMAT_Mumbai wrote:Hi,
Assuming y=4
The greatest integer less than y is 3 and the greatest integer equal to y is 4.
I am afraid this may not be right. The greatest integer lesser than or equal to 4 is 4.

hence, if y = 4; [y] = 4. hence, y-[y] = 0

If d = y-[y], then d is less than 1 indeed. Hence, sufficient.

In fact 0 <= d < 1.

Stmt 2:

[d] = 0 need not mean that d is only 0. d could be 0.1 or 0.2 or 0.9999999999999 or 0.111111111111.

But, it does mean that d < 1. Hence, sufficient.

Hence, D. Hope this helps. Thanks.
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