Number Properties + Decimals!!

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by sreak1089 » Mon Jan 18, 2010 8:39 am
I think ans is D IMO, Are you sure the OA is B?

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by apoorva.srivastva » Mon Jan 18, 2010 8:56 am
yes ans is B

statement 1:

for 0.49+0.49<1,
for 0.56+0.56>1

insufficent

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by sreak1089 » Mon Jan 18, 2010 9:26 am
oh yeah. you are right.. dammn my brain isn't working :(

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by apoorva.srivastva » Mon Jan 18, 2010 9:29 am
sreak1089 wrote:oh yeah. you are right.. dammn my brain isn't working :(
how do i attack statement B

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by sreak1089 » Mon Jan 18, 2010 9:57 am
For the product 0.ab and 0.cd to be > 0.5, I think 0.ab & 0.cd each should be > 0.5, thus the sum will be > 1.
Hence B is SUFFICIENT. Do you agree?
apoorva.srivastva wrote:
sreak1089 wrote:oh yeah. you are right.. dammn my brain isn't working :(
how do i attack statement B

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by Stuart@KaplanGMAT » Mon Jan 18, 2010 2:19 pm
sreak1089 wrote:For the product 0.ab and 0.cd to be > 0.5, I think 0.ab & 0.cd each should be > 0.5, thus the sum will be > 1.
Hence B is SUFFICIENT. Do you agree?
Correct.

If we had 1 * .5, we'd get .5. Since our first number has to be smaller than 1, our second number has to be greater than .5, giving us two numbers each of which is greater than .5.

Accordingly, the question becomes:

"Is the sum of two numbers greater than .5 more than 1?"

and we can definitely answer this with a "yes".
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by Due » Mon Jan 18, 2010 3:20 pm
use the fact that Arithmetic mean is greater than geometric mean. That will make it easy.