Ratio from GMAT prep

This topic has expert replies
Junior | Next Rank: 30 Posts
Posts: 24
Joined: Mon Mar 12, 2012 3:05 am

Ratio from GMAT prep

by jkelk » Mon Mar 12, 2012 3:12 am
The no. of stamps that Kaye & Albert had were in the ratio 5:3. After Kaye gave Albert 10 of her stamps, the ratio of the no. of stamps kaye had to the the no. Albert had was 7:5. As a result of this gift, Kaye had how many more stamps than Albert?

A. 20
B. 30
C. 40
D. 60
E. 90
Source: — Problem Solving |

Legendary Member
Posts: 581
Joined: Sun Apr 03, 2011 7:53 am
Thanked: 52 times
Followed by:5 members

by killer1387 » Mon Mar 12, 2012 3:21 am
K/A=5/3
(K-10)/(A+10)=7/5

A=90; K=150
AFTER GIFT DIFFERENCE=140-100=40

HENCE C

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 » Mon Mar 12, 2012 3:52 am
The no. of stamps that Kaye & Albert had were in the ratio 5:3. After Kaye gave Albert 10 of her stamps, the ratio of the no. of stamps kaye had to the the no. Albert had was 7:5. As a result of this gift, Kaye had how many more stamps than Albert?

A. 20
B. 30
C. 40
D. 60
E. 90
We can plug in the answer choices, which represent K-A after the gift.

Answer choice C: K-A = 40.
Since after the gift K:A = 7:5 = 70:50 = 140:100, K=140 and A=100.
Before the exchange of 10 stamps, K = 140+10 = 150 and A = 100-10 = 90.
150:90 = 5:3.
Success!

The correct answer is C.
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

GMAT/MBA Expert

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

by Anurag@Gurome » Mon Mar 12, 2012 5:22 am
jkelk wrote:The no. of stamps that Kaye & Albert had were in the ratio 5:3. After Kaye gave Albert 10 of her stamps, the ratio of the no. of stamps kaye had to the the no. Albert had was 7:5. As a result of this gift, Kaye had how many more stamps than Albert?

A. 20
B. 30
C. 40
D. 60
E. 90
Let the number of stamps that Kaye had = 5x
and the number of stamps that Albert had = 3x
When Kaye gave Albert 10 of her stamps, Kaye had 5x - 10 stamps and Albert had 3x + 10 stamps.
Then (5x - 10) : (3x + 10) = 7 : 5
5(5x - 10) = 7(3x + 10)
25x - 50 = 21x + 70
4x = 120
x = 30
Now Kaye had (5 * 30) - 10 = 150 - 10 = 140 stamps
and Albert had (3 * 30) + 10 = 90 + 10 = 100 stamps

Therefore, Kaye had 140 - 100 = 40 more stamps than Albert.

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/