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by grandh01 » Sat Aug 18, 2012 3:18 pm
In the formula ,V = 1/2r^3
if r is halved, then V is multiplied by
(A) 64
(B) 8
(C) 1
(D)1/8
(E)1/64
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by Brent@GMATPrepNow » Sat Aug 18, 2012 4:32 pm
grandh01 wrote:In the formula ,V = 1/2r^3
if r is halved, then V is multiplied by
(A) 64
(B) 8
(C) 1
(D)1/8
(E)1/64
This question is missing some brackets. The original question reads:

In the formula V = 1/(2r)^3, if r is halved, then V is multiplied by
A quick approach here is to plug in a "nice" number.
Let's plug in r=1. We get V = 1/[(2)(1)]^3 = 1/8

Now let's see what happens when we halve r. In other words, we'll plug in r=1/2.
We get V = 1/[(2)(1/2)]^3 = 1

So, when r=1, V=1/8, and when r=1/2, V=1.
So, when we halve r, V is multiplied by 8
Answer = B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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