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by ltl » Tue Dec 10, 2013 5:07 am
Would someone please explain this?
Thanks so much.

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by Brent@GMATPrepNow » Tue Dec 10, 2013 5:58 am
Here's one approach:

First recognize that √184,513 ≈ √180,000
Then we'll use the fact that √(xy) = (√x)(√y)

So, √180,000 = √[(18)(10,000)]
= (√18)(√10,000)
= (4.something)(100)
= some value between 400 and 500
= D

How do we know that √18 = 4.something?
Well, √16 = 4 and √25 = 5, so √18 must be BETWEEN 4 and 5

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by Brent@GMATPrepNow » Tue Dec 10, 2013 5:59 am
Here's another approach:

√160,000 = 400
√250,000 = 500
So, √184,513 must be BETWEEN 400 and 500
Answer: D

Cheers,
Brent
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by theCodeToGMAT » Tue Dec 10, 2013 9:50 am
Another approach:

In answer choices we see x00 .. so (x00)^2 = x0000.. compare this with question..

x = 18

==> sqrt(18) ==> between 4 & 5..as 4^2 = 16 & 5^2 = 25

So, 400 and 500

[spoiler]{D}[/spoiler]
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