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

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?

any comments?
Thanks!

I am on the same line .. but i doubt its 40 !!

Will be happy if i am proved wrong

Vishu

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

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?

My answer is C

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

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

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.

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.

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.

It is 40.

Original ratio = 5:3

Kaye - 150 Alberto- 90 (5:3)

After giving 10 stamps

Kaye - 140 Alberto- 100 (7:5)

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