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GMAT Prep / Number Properties
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jimmiejaz
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given from stmt 1, n^2 is divisible by 36
or we can write n^2 is divisible by (2^2*3^2)
or n is divisible by 2*3 hence suff.
from 2 we have
144/n^2 is an integer
144= 3^2*4^2
so, 144/4^2 is also an integer
If n =4, n is not divisible by 3 but if n=3, n is divisible
hence insuff.
Ans is A
or we can write n^2 is divisible by (2^2*3^2)
or n is divisible by 2*3 hence suff.
from 2 we have
144/n^2 is an integer
144= 3^2*4^2
so, 144/4^2 is also an integer
If n =4, n is not divisible by 3 but if n=3, n is divisible
hence insuff.
Ans is A
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lunarpower
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the above solution is good.
about statement (2), notice that it is a statement to which there is a very circumscribed set of solutions. when you see such statements, you would do well just to make an exhaustive list of their solutions.
if n^2 goes into 144 (that's what it means if the fraction turns out to be an integer), then, since 144 is a perfect square, n must go into √144 = 12.
therefore, the complete list of solutions to statement (2) is 1, 2, 3, 4, 6, 12.
try them one by one until either (a) you've used them all up, or (b) you've established insufficiency (after which you can quit testing, even if you haven't tried them all).
this approach doesn't work for statement (1), of course, as there are an infinity of numbers satisfying that statement.
about statement (2), notice that it is a statement to which there is a very circumscribed set of solutions. when you see such statements, you would do well just to make an exhaustive list of their solutions.
if n^2 goes into 144 (that's what it means if the fraction turns out to be an integer), then, since 144 is a perfect square, n must go into √144 = 12.
therefore, the complete list of solutions to statement (2) is 1, 2, 3, 4, 6, 12.
try them one by one until either (a) you've used them all up, or (b) you've established insufficiency (after which you can quit testing, even if you haven't tried them all).
this approach doesn't work for statement (1), of course, as there are an infinity of numbers satisfying that statement.
Ron has been teaching various standardized tests for 20 years.
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Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi
--
Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
--
Learn more about ron
