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GMAT prep

by sumatitandon » Sat Jan 10, 2009 4:22 am
The number of stamps that K and a had were in the ratio 5:3 respectively. After K gave A 10 of her stamps , the ratio of the number K had to the nuber of stamps A had was in the ratio 7:5. as aresult of this gift, K had how many more stamps than A?

20, 30, 40, 60, 90
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by mental » Sat Jan 10, 2009 5:20 am
Let the stamps with K and A after gift be: K=7x, A=5x

Difference in stamps after gift = K - A = 7x-5x = 2x

Before gift K had (7x+10), as K had given away 10 stamps
................A had (5x-10), as A had received 10 stamps

(7x+10)/(5x-10) = 5/3
21x + 30 = 25x - 50
80 = 4x
or 2x = 40 = Ans
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by pandeyvineet24 » Sat Jan 10, 2009 5:50 am
Answer should be 60.

K/A = 5/3 -- > K = 5A/3

(K-10)/(A+10) = 7/5

=> 5K - 50 = 7A + 70

=> 5K - 7A = 120

=> 25A/3 - 7A = 120

=> 4A = 120 *3
A = 90
K = 150
K-A = 60
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Re: GMAT prep

by logitech » Sat Jan 10, 2009 7:01 am
5x-10/3x+10=7/5 gives us X=30

5x-10-3x-10=2x-20 so 60-20 = 40
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by acecoolan » Sat Jan 10, 2009 7:25 pm
pandeyvineet24 wrote:Answer should be 60.

K/A = 5/3 -- > K = 5A/3

(K-10)/(A+10) = 7/5

=> 5K - 50 = 7A + 70

=> 5K - 7A = 120

=> 25A/3 - 7A = 120

=> 4A = 120 *3
A = 90
K = 150
K-A = 60
Vineet - As logitech and mental stated, the answer is 40. Since the question asks for the after scenario :-)

I almost made the same blunder

-A
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by logitech » Sat Jan 10, 2009 8:02 pm
acecoolan wrote:
pandeyvineet24 wrote:Answer should be 60.

K/A = 5/3 -- > K = 5A/3

(K-10)/(A+10) = 7/5

=> 5K - 50 = 7A + 70

=> 5K - 7A = 120

=> 25A/3 - 7A = 120

=> 4A = 120 *3
A = 90
K = 150
K-A = 60
Vineet - As logitech and mental stated, the answer is 40. Since the question asks for the after scenario :-)

I almost made the same blunder

-A
This is some type if mistake I hate to make. You have everything to answer the question but a careless comprehension of what question actually asks BITES you painfully.
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Re: GMAT prep

by Mr2Bits » Tue Jan 13, 2009 11:34 am
logitech wrote:5x-10/3x+10=7/5 gives us X=30

5x-10-3x-10=2x-20 so 60-20 = 40
Where did this equation come from?"

"5x-10-3x-10"
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by pandeyvineet24 » Tue Jan 13, 2009 12:41 pm
Ah ..i got that.

should have read the question more carefully.
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Re: GMAT prep

by logitech » Tue Jan 13, 2009 5:14 pm
Mr2Bits wrote:
logitech wrote:5x-10/3x+10=7/5 gives us X=30

5x-10-3x-10=2x-20 so 60-20 = 40
Where did this equation come from?"

"5x-10-3x-10"
ratio 5:3 respectively.
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