The answer is B
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Can someone please advise how to solve?
The answer is B
The answer is B
- RonPurewal
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You should be able to recognize right off the bat that this is a 'prime box' problem: it has to do with factors, divisibility, and the like. It's a little disguised - instead of directly mentioning divisibility, it shrouds it in the language of 'which of the following must be an integer?'.
In any case, the prime box for n^3 contains 450 times y, which is 3 x 3 x 5 x 5 x 2 x y.
But this is a perfect cube - which means that it must contain THREE (or six, or nine) of every prime factor in the box. This means that, at a bare minimum, 'y' must contain one 3, one 5, and two 2's.
The first option must be an integer, because we are dividing y only by factors that it is known to contain.
The second and third options don't have to be integers (we're dividing by numbers that contain one more '3' and one more '5', respectively, than we know 'y' to contain).
In any case, the prime box for n^3 contains 450 times y, which is 3 x 3 x 5 x 5 x 2 x y.
But this is a perfect cube - which means that it must contain THREE (or six, or nine) of every prime factor in the box. This means that, at a bare minimum, 'y' must contain one 3, one 5, and two 2's.
The first option must be an integer, because we are dividing y only by factors that it is known to contain.
The second and third options don't have to be integers (we're dividing by numbers that contain one more '3' and one more '5', respectively, than we know 'y' to contain).
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