GMAT prep question - I'm stumped! please help

harshavardhanc wrote:Here is a question in GMAT prep test 1 which stumped me!

I know the concept of prime factorization, the concept of factors of 5 etc which, I think, should be used here. But, I am not able to apply them together to reach to an answer.

An educated guess helped me get the credited response for this question, but I still don't know how to apply the concepts.

Any help would be appreciated!

OA D

sanju09 wrote:

harshavardhanc wrote:

I am not able to get to your URL

harshavardhanc wrote:

sanju09 wrote:

harshavardhanc wrote:

I am not able to get to your URL

sanju09 wrote:

harshavardhanc wrote:

sanju09 wrote:

harshavardhanc wrote:

I am not able to get to your URL

May be I am not in my perfect sight of eyes, so this is what I have read

If n is a multiple of 5 and n = p^2 q, where p and q are prime numbers, which of the following must be a multiple of 25?
(A) p^2
(B) q^2
(C) p q
(D) p^2 q^2
(E) p^2 q OR p^3 q (NOT SURE) it is p^3 * q

Either p or q must be 5 here. If p is 5, then p^2 q is a clear multiple of 25 (we’re not sure of it), and if q is 5, then another q multiplied to n will make it a definite multiple of 25. In other words, [spoiler]p^2 q^2[/spoiler] is a definite multiple of 25, no matter which of p and q is 5.

[spoiler]D[/spoiler]

harshavardhanc wrote:

sanju09 wrote:

harshavardhanc wrote:

sanju09 wrote:

harshavardhanc wrote:

I am not able to get to your URL

May be I am not in my perfect sight of eyes, so this is what I have read

If n is a multiple of 5 and n = p^2 q, where p and q are prime numbers, which of the following must be a multiple of 25?
(A) p^2
(B) q^2
(C) p q
(D) p^2 q^2
(E) p^2 q OR p^3 q (NOT SURE) it is p^3 * q

Either p or q must be 5 here. If p is 5, then p^2 q is a clear multiple of 25 (we’re not sure of it), and if q is 5, then another q multiplied to n will make it a definite multiple of 25. In other words, [spoiler]p^2 q^2[/spoiler] is a definite multiple of 25, no matter which of p and q is 5.

[spoiler]D[/spoiler]

soooper! you rock! thanks !!

I got stuck after getting two possibilities. the time was running fast and couldn't think of the product with additional q.

Time!!!!... how to beat it!!