Target Test Prep 20% Off Flash Sale is on! Code: FLASH20

Redeem
Target Test Prep
5-Day Free Trial
5-day free, full-access trial TTP

Available with Beat the GMAT members only code

MORE DETAILS
Target Test Prep
Magoosh
Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

MORE DETAILS
Magoosh

Least possible value

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 46
Joined: Mon Aug 25, 2008 9:06 am
Thanked: 1 times

Least possible value

by madsport » Mon Sep 15, 2008 11:39 am
If x, y, and z are positive integers and 3x = 4y = 7z, then the least possible value of x + y + z is

(A) 33
(B) 40
(C) 49
(D) 61
(E) 84

The answer is D

I have no clue how to solve this one
Top
Junior | Next Rank: 30 Posts
Posts: 17
Joined: Sun Sep 14, 2008 1:19 pm
Thanked: 4 times

by alescau » Mon Sep 15, 2008 11:58 am
since the coefficients are prime numbers, nothing simplifies.
to make the equality stand, x=4*7, y=3*7, z=3*4. add them up and get 61.
Top
Senior | Next Rank: 100 Posts
Posts: 46
Joined: Mon Aug 25, 2008 9:06 am
Thanked: 1 times

by madsport » Mon Sep 15, 2008 1:33 pm
how did you come up with this arrangement --->x=4*7, y=3*7, z=3*4?
Top
Legendary Member
Posts: 1153
Joined: Wed Jun 20, 2007 6:21 am
Thanked: 146 times
Followed by:2 members

by parallel_chase » Mon Sep 15, 2008 1:39 pm
madsport wrote:how did you come up with this arrangement --->x=4*7, y=3*7, z=3*4?
3x=4y=7z

LCM = 84

x = 28
y = 21
z = 12

28+21+12 = 61
Top
Legendary Member
Posts: 891
Joined: Sat Aug 16, 2008 4:21 am
Thanked: 27 times
Followed by:1 members
GMAT Score:660(

by 4meonly » Tue Sep 16, 2008 1:16 am
3x=4y=7z

z=3x/7
y=3x/4

x + y + z = x + 3x/4 + 3x/7 = 61x/28
to make 61x/28 an integer minimum value of x is 28, because 61 is prime number
so 28 + 30*28/4 + 3*28/7 = 61

Answer D
Top
Post new topic Post Reply
• Page 1 of 1