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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

Number of Stamps - GMAT Prep Question - Please help

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 22
Joined: Sun Dec 21, 2008 7:19 pm
by rjanardhanan » Tue Feb 14, 2012 8:13 pm
The number of stamps that Kaye and Alberto had were in the ratio 5:3 respectively.After Kaye gave Alberto 10 of her stamps,the ratio of the number Kaye had to the number Alberto had was 7:5.As a result of this gift,Kaye had how many more stamps than Alberto?

20
30
40
60
90
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members
Location: Milpitas, CA
Thanked: 1854 times
GMAT Score:770

by Anurag@Gurome » Tue Feb 14, 2012 8:20 pm
rjanardhanan wrote:The number of stamps that Kaye and Alberto had were in the ratio 5:3 respectively.After Kaye gave Alberto 10 of her stamps,the ratio of the number Kaye had to the number Alberto had was 7:5.As a result of this gift,Kaye had how many more stamps than Alberto?

20
30
40
60
90
Let us assume that Kaye and Alberto now have 7x and 5x stamps respectively. Hence, now Kaye has 2x more stamps than Alberto.

Now, before Kaye gave Alberto 10 stamps, Kaye had (7x + 10) stamps and Alberto had (5x - 10).

So, (7x + 10)/(5x - 10) = 5/3
(21x + 30) = (25x - 50)
4x = 80
2x = 40

The correct answer is C.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Junior | Next Rank: 30 Posts
Posts: 26
Joined: Thu Dec 04, 2008 9:19 pm
Location: Bangalore
Thanked: 1 times

by dhiren8182 » Tue Feb 14, 2012 8:42 pm
Hi Anurag,
I solved it in some other way.
Is this right or wrong?

No of stamps Kaye and Alberto had be 5x and 3x respectively.
Now Kaye gives away 10 stamps so no of stamps Kaye has is 5x-10 and that Alberto has is 3x+10
So 5x-10/3x+10=7/5
=>25x-50=21x+70
=>4x=120
=>x=30
Substituting value of x in 5x-10 we 140 and substituting value of x in 3x+10 we get 100.
Difference of two=40 so Ans is D.
Is this the right approach.
Dhiren
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Tue Feb 14, 2012 8:48 pm
I posted an alternate solution here:

https://www.beatthegmat.com/number-of-st ... 02294.html
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
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pmFollowed by: 523 members
Location: Milpitas, CA
Thanked: 1854 times
GMAT Score:770

by Anurag@Gurome » Tue Feb 14, 2012 9:02 pm
dhiren8182 wrote:Hi Anurag,
I solved it in some other way.
Is this right or wrong?

No of stamps Kaye and Alberto had be 5x and 3x respectively.
Now Kaye gives away 10 stamps so no of stamps Kaye has is 5x-10 and that Alberto has is 3x+10
So 5x-10/3x+10=7/5
=>25x-50=21x+70
=>4x=120
=>x=30
Substituting value of x in 5x-10 we 140 and substituting value of x in 3x+10 we get 100.
Difference of two=40 so Ans is D.
Is this the right approach.
Dhiren
This approach is also correct Dhiren, the correct answer is C, not D.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 425
Joined: Wed Dec 08, 2010 9:00 amFollowed by: 7 members
Thanked: 56 times
GMAT Score:690

by LalaB » Tue Feb 14, 2012 10:53 pm
dhiren8182 wrote:Hi Anurag,
I solved it in some other way.
Is this right or wrong?

No of stamps Kaye and Alberto had be 5x and 3x respectively.
Now Kaye gives away 10 stamps so no of stamps Kaye has is 5x-10 and that Alberto has is 3x+10
So 5x-10/3x+10=7/5
=>25x-50=21x+70
=>4x=120
=>x=30
Substituting value of x in 5x-10 we 140 and substituting value of x in 3x+10 we get 100.
Difference of two=40 so Ans is D.
Is this the right approach.
Dhiren
or

x=30

we need to find (5x-10)-(3x+10)=2x-20 =2*30-20=40
Happy are those who dream dreams and are ready to pay the price to make them come true.(c)

In order to succeed, your desire for success should be greater than your fear of failure.(c)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 641
Joined: Tue Feb 14, 2012 3:52 pmFollowed by: 8 members
Thanked: 11 times

by gmattesttaker2 » Sat Oct 06, 2012 7:46 am
Hello,

I tried to solve as follows:

K:A = 5x - 10 : 3x + 10

5x - 10
-------- = 7/5
3x + 10

So, x = 30


Now, 7x/5x = 7(30)/5(30)= 210/150

So, Kaye has 60 more stamps than Alberto. I was just wondering why plugging in x in 7x/5x is in-correct? Thanks for your help.

Best Regards,
Sri
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 130
Joined: Fri Apr 20, 2012 8:13 amFollowed by: 4 members
Location: Toronto, Ontario
Thanked: 16 times
GMAT Score:650

by tisrar02 » Wed Jan 23, 2013 4:41 pm
Well you were correct all the way up until you had to sub X=30 back into the equation.

K= 5(30)-10= 140

A= 3(30)+10= 100

Thus you have a difference of 40. Answer choice C
gmattesttaker2 wrote:Hello,

I tried to solve as follows:

K:A = 5x - 10 : 3x + 10

5x - 10
-------- = 7/5
3x + 10

So, x = 30


Now, 7x/5x = 7(30)/5(30)= 210/150

So, Kaye has 60 more stamps than Alberto. I was just wondering why plugging in x in 7x/5x is in-correct? Thanks for your help.

Best Regards,
Sri
Dedication is what leads to success...
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1