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Exponents Question

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by DFritschy » Mon Aug 27, 2012 2:34 pm
[ 10^8 - 10^2 ] / [ 10^7 - 10^3 ] is closest to which of the following?

a) 10^4 b) 10 c) 10^9 d) 100 e) 10^6


incase the answer choices seem weird...I only wrote down the correct answer so I made up the other 4!
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Source: — Problem Solving |

by Brent@GMATPrepNow » Mon Aug 27, 2012 3:28 pm
DFritschy wrote:[ 10^8 - 10^2 ] / [ 10^7 - 10^3 ] is closest to which of the following?

a) 10^4 b) 10 c) 10^9 d) 100 e) 10^6
Relatively speaking, 10^2 is quite insignificant when compared to 10^8. Similarly, 10^3 is quite insignificant when compared to 10^7.

As such, 10^8 - 10^2 is very close to 10^8.
Notice that 10^8 = 100,000,000 and, from this amount, we are subtracting 100. The result will be very close to 10^8.

Similarly, 10^7 - 10^3 is equal to 10,000,000 - 1000, so the result will be very close to 10^7.

So....[10^8 - 10^2] / [10^7 - 10^3] is close to (10^8)/(10^7) and (10^8)/(10^7) = 10.

So, the answer is B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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