GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 16 Aug 2018, 16:44

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# If x, y, and z are positive integers and 3x = 4y = 7z, then

Author Message
TAGS:

### Hide Tags

Manager
Status: Current MBA Student
Joined: 19 Nov 2009
Posts: 120
Concentration: Finance, General Management
GMAT 1: 720 Q49 V40
If x, y, and z are positive integers and 3x = 4y = 7z, then  [#permalink]

### Show Tags

16 May 2011, 15:35
00:00

Difficulty:

25% (medium)

Question Stats:

88% (01:07) correct 12% (02:29) wrong based on 17 sessions

### HideShow timer Statistics

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
Director
Joined: 01 Feb 2011
Posts: 671
Re: GMAC paper test question  [#permalink]

### Show Tags

16 May 2011, 17:51
1
given 3x=4y=7z

x+y+z in terms of x

= x+(3x/4)+(3x/7) = 61x/28

now checking with each of the answers and see which value gives a minimum integer value.

A x = 28*33/61 , not an integer

B,C can be ruled out similarly.

D is minimum value as x = 61*28/61 = 28

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8187
Location: Pune, India
Re: GMAC paper test question  [#permalink]

### Show Tags

16 May 2011, 17:59
1
tonebeeze wrote:
Can someone walk me through this one. thanks

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

My solution in another post:

When I see more than one '=', my instinct is to make them equal to k to get to a 'common ground'. Thereafter, it is easier to think in terms of just one variable.

$$3x = 4y = 7z = k$$

$$x = \frac{k}{3}; y = \frac{k}{4}; z = \frac{k}{7}$$
Now, all x, y and z are positive integers so k should be divisible by 3, 4 and 7. The minimum value of k will be 3*4*7.

$$x + y + z = \frac{k}{3} + \frac{k}{4} + \frac{k}{7} = \frac{3*4*7}{3} + \frac{3*4*7}{4} + \frac{3*4*7}{7} = 61$$[/quote]
_________________

Karishma
Veritas Prep GMAT Instructor

Save up to \$1,000 on GMAT prep through 8/20! Learn more here >

GMAT self-study has never been more personalized or more fun. Try ORION Free!

Current Student
Joined: 08 Jan 2009
Posts: 309
GMAT 1: 770 Q50 V46
Re: GMAC paper test question  [#permalink]

### Show Tags

16 May 2011, 20:30
1
3x = 4y = 7z

LCM = 3 * 4 * 7 = 84
84 / 3 = 28
84 / 4 = 21
84 / 7 = 12

28 + 21 + 12 = 61
VP
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1125
Re: GMAC paper test question  [#permalink]

### Show Tags

16 May 2011, 20:44
y=3/4x and z=3/7x

x+y+z = 61/28 *x = 61 for x=1.
_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

Re: GMAC paper test question &nbs [#permalink] 16 May 2011, 20:44
Display posts from previous: Sort by

# Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.