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Cube Root Question

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Cube Root Question

by deagez » Sat Apr 04, 2009 2:50 am
Question is

[(.000064)^1/3]^1/2

A) .0004
B) .008
C) .02
D) .04
E) .2

I mean with guess and check it is easy to figure this out in less than 30 seconds, but just out of curiosity can anyone think of a quick way to do the cube root of .000064 if we didn't have choices?
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Re: Cube Root Question

by Ian Stewart » Sat Apr 04, 2009 4:39 am
You can convert decimals to fractions:

[(.000064)^1/3]^1/2 = [(64/10^6)^1/3]^1/2 = (4/10^2)^1/2 = 2/10
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by cramya » Sat Apr 04, 2009 4:51 pm
but just out of curiosity can anyone think of a quick way to do the cube root of .000064 if we didn't have choices?
Cube root of 64 is 4

We have six digits after decimal so it will be .04

.2 * .2 = .04

Hence .2
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