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

Redeem

GMATPrep Stamps

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 21
Joined: Sun Apr 20, 2008 7:38 pm
Location: North Carolina

GMATPrep Stamps

by Schrute Beets » Wed Jul 16, 2008 6:54 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?

A) 20
B) 30
C) 40
D) 60
E) 90

Thanks!
Top
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 62
Joined: Fri Dec 21, 2007 2:58 pm
Location: Fremont , California
Thanked: 3 times

by kishore » Wed Jul 16, 2008 7:17 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?

C) 40

K:A = 5:3 => K = 5x and A = 3x

After Kaye gave Alberto 10 of her stamps

K: A = 5x-10 : 3x+10 = 7:5

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

5(5x-10) = 7(3x+10)

25x-50 = 21x+70 => x = 30

K = 5x-10 = 5(30)-10 = 140
A = 3x+10 = 3(30)+10 = 100

K-A = 140-100 = 40
Top
Master | Next Rank: 500 Posts
Posts: 315
Joined: Thu Aug 17, 2006 10:43 pm
Thanked: 23 times

by Suyog » Tue Aug 26, 2008 1:06 pm
Kaye and Alberto ratio is 5:3

when we say ans is C i.e. 40

then Kaye and Albert can be 100:60 i.e. 5:3 right?

now, after Kaye gave Alberto 10 of her stamps, the ratio of the number Kaye had to the number Alberto had was 7:5

the number of stamps should be 90:70 which is not 7:5

but if we take D i.e. 60

then say Kaye and Albert is 150:90 (i.e. 5:3)
now if Kaye gives 10 stamps to Alberto then its 140:100 which is 7:5

I'm making some stupid mistake... but wot is it? :(
Top
Master | Next Rank: 500 Posts
Posts: 315
Joined: Thu Aug 17, 2006 10:43 pm
Thanked: 23 times

by Suyog » Tue Aug 26, 2008 6:22 pm
any comments?
Thanks!
Top
Legendary Member
Posts: 574
Joined: Sun Jun 01, 2008 8:48 am
Location: Bangalore
Thanked: 28 times

by vishubn » Tue Aug 26, 2008 6:31 pm
I am on the same line .. but i doubt its 40 !!

Will be happy if i am proved wrong

Vishu
Top
Master | Next Rank: 500 Posts
Posts: 105
Joined: Tue Jul 15, 2008 7:03 pm
Thanked: 5 times

by pre-gmat » Tue Aug 26, 2008 6:58 pm
K:A = 5:3 => ket kaye have K stamps and Alberto A stamps

K/A= 5/3

or 3K=5A


After Kaye gave Alberto 10 of stamps

Kaye has k-10 and alberto A+10

5K-10/3A+10 = 7/5

5(5K-10) = 7(3K+10)

5k-7A=120

we know that K=5/3A

25A-21A=360
A=90 and K =150

Therefore K-A = 150-90 = 60
Top
Legendary Member
Posts: 1161
Joined: Mon May 12, 2008 2:52 am
Location: Sydney
Thanked: 23 times
Followed by:1 members

by mehravikas » Tue Aug 26, 2008 7:24 pm
Answer should be 40, because the last sentence of the question says, as a result of this what is the difference. 140/100 = 7/5

Difference = 40.

Can we have the official answer please?
Top
Newbie | Next Rank: 10 Posts
Posts: 5
Joined: Sat Aug 23, 2008 10:02 pm

ans

by john555 » Tue Aug 26, 2008 7:34 pm
My answer is C
Top
Master | Next Rank: 500 Posts
Posts: 105
Joined: Tue Jul 15, 2008 7:03 pm
Thanked: 5 times

by pre-gmat » Tue Aug 26, 2008 9:08 pm
Sorry I understood the problem and corrected the solution:


K:A = 5:3 => let kaye have K stamps and Alberto A stamps

K/A= 5/3

or 3K=5A


After Kaye gave Alberto 10 of stamps

Kaye has k-10 and alberto A+10

5K-10/3A+10 = 7/5

5(5K-10) = 7(3K+10)

5k-7A=120

we know that K=5/3A

25A-21A=360
A=90 and K =150

after the stamp exchange:

A has 100
and K has 150-10=140

difference = 40

K-A=40
Top
Junior | Next Rank: 30 Posts
Posts: 18
Joined: Thu Jun 26, 2008 9:12 am

by xunil56 » Sun Sep 28, 2008 10:06 pm
mehravikas wrote:Answer should be 40, because the last sentence of the question says, as a result of this what is the difference. 140/100 = 7/5

Difference = 40.

Can we have the official answer please?
OA: 40
Top
Legendary Member
Posts: 1169
Joined: Sun Jul 06, 2008 2:34 am
Thanked: 25 times
Followed by:1 members

by aj5105 » Tue Oct 07, 2008 9:12 pm
The ratio of stamps of Kaye and Alberto is 5:3.
Then the total stamps Kaye has = 5x and the total stamps Alberto has is 3x.

Now,Kaye gives 10 stamps to Alberto.
It means Kaye has 5x-10 stamps and Alberto has 3x + 10 stamps. That is in the ratio 7:5.Cal x.Cal 5x-10 , cal 3x+10.Subtract.We get 40.
Top
Junior | Next Rank: 30 Posts
Posts: 21
Joined: Tue Feb 12, 2008 12:50 pm

Guess work

by getk » Wed Oct 08, 2008 6:52 am
Not a standard method, but this is the way i solved..

via the multiples of LCM of the ratio's..

eg 1st ratio is 5:3 (so 8 is the base 5+3)
2nd ratio is : 7:5 (12 is base)

LCM of 8 and 12 is 24

24, 48, 72, 96, 120, 240 etc..

hit and try using 120
1st ratio is 75:45
2nd 70:50
this could be correct if "5" was decreased. So for 10, try it using 240 :)
150: 90
140:100 --> ans(difference is 40)
bingo !!

its hard to explain in paper, but logically it would be easy to think.
Top
Legendary Member
Posts: 833
Joined: Mon Aug 04, 2008 1:56 am
Thanked: 13 times

by vivek.kapoor83 » Wed Oct 08, 2008 11:25 am
Suyog wrote:Kaye and Alberto ratio is 5:3

when we say ans is C i.e. 40

then Kaye and Albert can be 100:60 i.e. 5:3 right?

now, after Kaye gave Alberto 10 of her stamps, the ratio of the number Kaye had to the number Alberto had was 7:5

the number of stamps should be 90:70 which is not 7:5

but if we take D i.e. 60

then say Kaye and Albert is 150:90 (i.e. 5:3)
now if Kaye gives 10 stamps to Alberto then its 140:100 which is 7:5




I'm making some stupid mistake... but wot is it? :(




Basic funda is that, if u multiply any no. or ratio with some num then , u have to do the reverse operation on it as well.
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Wed Oct 08, 2008 6:20 pm
It is 40.

Original ratio = 5:3

Kaye - 150 Alberto- 90 (5:3)

After giving 10 stamps

Kaye - 140 Alberto- 100 (7:5)
Top
Junior | Next Rank: 30 Posts
Posts: 10
Joined: Thu Nov 20, 2008 10:04 am

by zeppelin » Wed Aug 26, 2009 7:32 am
I solved in the same manner as done by pre-gmat
Please help!!
x/y = 5/3
Then why are we taking

5x-10/3y+10= 7/5
Shouldn't it be

x-10/y+10= 7/5
Top
Post new topic Post Reply