number system

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 468
Joined: Mon Jul 25, 2011 10:20 pm
Thanked: 29 times
Followed by:4 members

number system

by vipulgoyal » Thu Jan 16, 2014 1:32 am
If P*Q is the factor of m*P+n*Q, which of the following must be true?
I. P is factor of m*n.
II. P is factor of m.
III. P*Q is factor of m*P
(A) I only
(B) II only
(C) III only
(D) I and II
(E) None
E

Is there another way other then substitution ?????
Source: — Problem Solving |

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Thu Jan 16, 2014 5:18 am
vipulgoyal wrote:If P*Q is the factor of m*P+n*Q, which of the following must be true?
I. P is factor of m*n.
II. P is factor of m.
III. P*Q is factor of m*P
(A) I only
(B) II only
(C) III only
(D) I and II
(E) None
E
Try to DISPROVE the statements, each of which describes p as a factor of another value.
If p=q, then neither p nor q must divide into m or n.
Let p=q=3, m=5 and n=7, so that pq=9 and mp + nq = 5*3 + 7*3 = 36.

I: p=3 is not a factor of mn=35.
II: p=3 is not a factor of m=5.
III: pq = 9 is not a factor of mp=15.

Thus, none of the statements must be true.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3