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# Fractions/Decimals/Percents

Author Message
Manager
Joined: 05 May 2005
Posts: 64

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17 Aug 2007, 17:43
How would you solve?

If 125% of j is equal to 25% of k, 150% of k is equal to 50% of l, and 175% of l is equal to 75% of m, then 20% of m is equal to what percent of 200% of j ?

a) .35
b) 3.5
c) 35
d) 350
e) 3500

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Director
Joined: 09 Jul 2007
Posts: 845
Location: London

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17 Aug 2007, 18:04
above720 wrote:
How would you solve?

If 125% of j is equal to 25% of k, 150% of k is equal to 50% of l, and 175% of l is equal to 75% of m, then 20% of m is equal to what percent of 200% of j ?

a) .35
b) 3.5
c) 35
d) 350
e) 3500

it takes ages

1) 125j=25k <=> 5j=k
2) 150k=50l <=> 3k=l
3) 175l=75m <=> 7l=3m

so start substiuting one by one.
1 and 2 gives us 15j=l
2 and 3 gives us 7*15j=3m <=> 35j=m
(m/j)=35

now the problem asks x% which can be
20m=200j*x <=> m=10jx
x = m/(10j) or (m/j)*(1/10)
x =35/10=3.5
Director
Joined: 12 Jul 2007
Posts: 661

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17 Aug 2007, 19:51
1
ouch, no way this can be a real GMAT problem! way too slow

5/4J = 1/4K
3/4K = 2/4L
7/4L = 3/4M

OR multiply out by 4

5J = K
3K = 2L
7L = 3M

then do all the crazy math to carry it through. it takes forever!
Senior Manager
Joined: 09 Aug 2006
Posts: 404

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17 Aug 2007, 23:21
1
above720 wrote:
How would you solve?

If 125% of j is equal to 25% of k, 150% of k is equal to 50% of l, and 175% of l is equal to 75% of m, then 20% of m is equal to what percent of 200% of j ?

a) .35
b) 3.5
c) 35
d) 350
e) 3500

Ans is D. : 350.

Its simple :

5/4 J = 1/4K
6/4 K = 1/2 I
7/4 I = 3/4 M

Hence,
M = 7/3 I
M = 7K ( I = 3K)
M = 35 J (K= 5J )

1/5M = 7J
200% of J = 2J

So, (7J / 2J) * 100 = 350
Intern
Joined: 01 Aug 2007
Posts: 35

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18 Aug 2007, 00:08
I wouldn't doubt that this is an actual GMAT problem...

I got this problem on GMATPrep once and was able to solve it relatively quickly (~1 min) by plugging in smart numbers... I'm too lazy to re-do it right now, but I know that you can choose numbers that work well w/ those percentages that make this problem really easy.
GMAT Instructor
Joined: 04 Jul 2006
Posts: 1126

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18 Aug 2007, 03:00
above720 wrote:
How would you solve?

If 125% of j is equal to 25% of k, 150% of k is equal to 50% of l, and 175% of l is equal to 75% of m, then 20% of m is equal to what percent of 200% of j ?

a) .35
b) 3.5
c) 35
d) 350
e) 3500

m/5 * ((7L/4)/(3M/4))(3K/2)/(L/2)((5J/4)/(k/4))= 1/5 (7/3)(3)(5)=7J

20% of m is 700% of J and thus 350% of 2J
Manager
Joined: 18 Jun 2007
Posts: 73

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18 Aug 2007, 07:20
It took me more than 3 mins to solve this problem..

125j/100 = 25K/100
150K/100 = 50i/100
175i/100 = 75m

5J = k
3K = i
7i = 3m

Substituting values

m = 35J

20/100 m = x/100 of ( 200/100 j)
20m =2Jx
x= 10m/j
x= 10 X 35J/j
x= 350

I do want to know an easier way to solve this.. Any suggestions? Smart numbers? and how to go about it..

Also - I do agree that MGMAT is super good to learn concepts..But how in the world do you keep up with remembering all the strategies?? Do you constantly keep revising them?

THanks!!

Btw- My first post - SOLVING a prblem
Non-Human User
Joined: 09 Sep 2013
Posts: 13740

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29 Oct 2018, 18:08
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Re: Fractions/Decimals/Percents   [#permalink] 29 Oct 2018, 18:08
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