Both a and b are positive; what is the value of a?
(1) 150 percent of a equals 450 percent of b.
(2) ab is the cube of a positive integer.
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Both a and b are positive; what is the value of a?
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deepak_free
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gmatmachoman
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deepak_free wrote:Both a and b are positive; what is the value of a?
(1) 150 percent of a equals 450 percent of b.
(2) ab is the cube of a positive integer.
st 1: Insufficient
a= 3b
st 2:
ab = X^3
Insufficient
Combining st 1 & st 2;
we have 3b^2 = X^3
solving for X = 3
we get b =3,a=9
Pick C
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deepak_free
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Do you really think
3b^2=X^3
will result only in 3 even if it is not provided that x is an integer
3b^2=X^3
will result only in 3 even if it is not provided that x is an integer
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barcebal
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Just because, when combining statements 1 and 2, the cube root of 3b^2 equals an integer doesn't mean that b has to be 3.
B could also be 81.
3(81^2)=27^3
Therefore both are insufficient.
Hope that helps.
B could also be 81.
3(81^2)=27^3
Therefore both are insufficient.
Hope that helps.
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gmatmachoman
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The st 2 says that X is a positive integer..is n't it???deepak_free wrote:Do you really think
3b^2=X^3
will result only in 3 even if it is not provided that x is an integer
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outreach
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if b=81 then a=27
now 2781 is not a cube root of any number
so it will be incorrect..
any opinion on the same??
now 2781 is not a cube root of any number
so it will be incorrect..
any opinion on the same??
barcebal wrote:Just because, when combining statements 1 and 2, the cube root of 3b^2 equals an integer doesn't mean that b has to be 3.
B could also be 81.
3(81^2)=27^3
Therefore both are insufficient.
Hope that helps.
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barcebal
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A is 3 times b, not the other way around.outreach wrote:if b=81 then a=27
now 2781 is not a cube root of any number
so it will be incorrect..
any opinion on the same??
barcebal wrote:Just because, when combining statements 1 and 2, the cube root of 3b^2 equals an integer doesn't mean that b has to be 3.
B could also be 81.
3(81^2)=27^3
Therefore both are insufficient.
Hope that helps.
So if B is 81, then a is actually 243 and AB=19683, and the cube root of that is 27.
