BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Divisibility Problem

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 54
Joined: Tue Sep 20, 2011 7:58 am
Thanked: 1 times
Followed by:1 members

Divisibility Problem

by sparkle6 » Mon Sep 26, 2011 8:09 am
If x and y are positive integers, which of the following CANNOT be the greatest common divisor of 35x and 20y?

a. 5

b. 5(x - y)

c. 20x

d. 20y

e. 35x

[spoiler]Answer: C. I narrowed it down to B or C, but then could not find a way to eliminate either one. Any solutions?[/spoiler]
Top
Source: — Problem Solving |
User avatar
Legendary Member
Posts: 1309
Joined: Mon Apr 04, 2011 5:34 am
Location: India
Thanked: 310 times
Followed by:123 members
GMAT Score:750

by cans » Mon Sep 26, 2011 8:22 am
35x and 20y.
35x = 5*7*x and 20y = 5*4*y
a) 5 is possible.
E) when y=35x possible
D) when x=20y, possible
take C)
if 20x is GCD,
20x = 5*4*x.
but 35x is 5*7*x. how can we get 4?? not possible
If my post helped you- let me know by pushing the thanks button ;)

Contact me about long distance tutoring!
[email protected]

Cans!!
Top
Post new topic Post Reply
• Page 1 of 1