MGMAT HW Bank - If 2 and 13 are factors of positive integer

[rockrock]

From the HW banks...

If 2 and 13 are factors of positive integer p, then which of the following COULD be divisible by p?

I. 13
II. 26
III. 52

None
I only
I and II only
III only
II and III only

Ron showed us how to use prime boxes instead of trees? But for this type of problem, I find it easy to use a tree instead to remind me to move "up" the tree instead of "down".... How would I use a box here? To maintain consistency of process.....

[RonPurewal]

From the HW banks...

If 2 and 13 are factors of positive integer p, then which of the following COULD be divisible by p?

...
Ron showed us how to use prime boxes instead of trees? But for this type of problem, I find it easy to use a tree instead to remind me to move "up" the tree instead of "down".... How would I use a box here? To maintain consistency of process.....

remember -- if "X is a factor of Y", or, equivalently, "Y is divisible by X" or "Y is a multiple of X", then this means that X is in the prime box of Y.

so:
* 2 and 13 are in the prime box of "p".
* "p" itself is in the prime box of the number that we want.

so:
the prime box of "p" is
{ 2 13 (possibly others) }

we want another number that is DIVISIBLE BY this quantity, so we want another number whose prime box contains
{ 2 13 (possibly others) }
so, 13 is out, but 26 and 52 are ok.

--

by the way, two things:

(1) this was posted in the wrong folder -- you originally used the gmat prep folder.
i'll move this post to the correct folder this time, but in the future please pay attention to the folder in which you are posting.

(2) whenever you're posting a problem, please post the answer to the problem.

thanks!