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PS - water poured

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Xbond: Master | Next Rank: 500 Posts; Posts: 275; Joined: Wed Jul 02, 2008 4:19 am; Thanked: 4 times

by Xbond » Fri Sep 11, 2009 10:44 am

Hi there,

Could you give me your ELEGANT, QUICK, and EFFICIENT method to resolve (with these concepts and with finding the solution).

Equal amounts of water were poured into two empty jars of different capacities, which made one jar Â¼ full
and the other jar 1/3 full. If the water in the jar with the lesser capacity is then poured into the jar with greater capacity, what fraction of the larger jar will be filled with water?

a)1/7
b)2/7
c)Â½
d)7/12
e)2/3

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Source: Beat The GMAT — Problem Solving | Fri Sep 11, 2009 10:44 am

Nermal: Senior | Next Rank: 100 Posts; Posts: 77; Joined: Sun Jun 21, 2009 10:25 am; Location: Germany; Thanked: 7 times

by Nermal » Fri Sep 11, 2009 12:03 pm

I find picking numbers easiest on this question:

jar with capacity of 9 liters and
jar with capacity of 12 liters.

Pour 3 liters into each of them (smaller one: 3/9=1/3; bigger one: 3/12=1/4).
Now pour the 3 liters of the smaller jar into the bigger one and you get 6/12=1/2

Answer C (1/2)

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Xbond: Master | Next Rank: 500 Posts; Posts: 275; Joined: Wed Jul 02, 2008 4:19 am; Thanked: 4 times

by Xbond » Sat Sep 12, 2009 9:24 am

many thks

OA is C

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Ian Stewart: GMAT Instructor; Posts: 2623; Joined: Mon Jun 02, 2008 3:17 amFollowed by: 355 members; Location: Montreal; Thanked: 1090 times; GMAT Score:780

Re: PS - water poured

by Ian Stewart » Sat Sep 12, 2009 11:59 am

Xbond wrote: Equal amounts of water were poured into two empty jars of different capacities, which made one jar Â¼ full
and the other jar 1/3 full. If the water in the jar with the lesser capacity is then poured into the jar with greater capacity, what fraction of the larger jar will be filled with water?

a)1/7
b)2/7
c)Â½
d)7/12
e)2/3

The jar with lesser capacity is the one which is most full, so we pour the water from the jar which is 1/3 full into the jar which is 1/4 full. Since the amounts of water are equal, this will double the water in the 1/4 full jar, leaving us with a jar which is 1/2 full.

For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

ianstewartgmat.com

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sudi760mba: Senior | Next Rank: 100 Posts; Posts: 85; Joined: Wed Aug 13, 2008 2:21 am; Thanked: 1 times

Re: PS - water poured

by sudi760mba » Wed Sep 16, 2009 2:50 am

Some of these questions are best with numbers picked.

Jar A: Capacity = 12 litres
A: 1/4 * 12 = 3 litres

Jar B: We need to use the same amount so we set x(capacity of B) to 3 litres.

1/3 * x = 3 litres
x = 9 litres
Jar B: 9 litres

3 litres + 3 litres = 6 litres
6/12 = 1/2
C

Xbond wrote:Hi there,

Could you give me your ELEGANT, QUICK, and EFFICIENT method to resolve (with these concepts and with finding the solution).

Equal amounts of water were poured into two empty jars of different capacities, which made one jar Â¼ full
and the other jar 1/3 full. If the water in the jar with the lesser capacity is then poured into the jar with greater capacity, what fraction of the larger jar will be filled with water?

a)1/7
b)2/7
c)Â½
d)7/12
e)2/3

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isaaczx: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Tue Oct 06, 2009 11:18 pm

by isaaczx » Tue Oct 06, 2009 11:20 pm

1/4 A = 1/3 B
A' = 1/4A + 1/3B
So A' = 1/4A + 1/4A = 1/2A

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ikaplan: Master | Next Rank: 500 Posts; Posts: 181; Joined: Fri Sep 04, 2009 12:06 pmFollowed by: 1 member; Thanked: 17 times

by ikaplan » Mon Dec 19, 2011 11:05 am

Thanks

"Commitment is more than just wishing for the right conditions. Commitment is working with what you have."

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LalaB: Master | Next Rank: 500 Posts; Posts: 425; Joined: Wed Dec 08, 2010 9:00 amFollowed by: 7 members; Thanked: 56 times; GMAT Score:690

by LalaB » Mon Dec 19, 2011 12:10 pm

lets assume, that amount of water= 1

then-

1=1/3*C1 (C1=Capacity of jar 1) C=3

1=1/4*C2 C2=4

from above info, we can easily assume that jar 1 is with lesser capacity. so, we add the amount of water of jar 1 to the amount of water of jar 2.

now we have (1+1)/4 =1/2

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pemdas: Legendary Member; Posts: 1084; Joined: Fri Apr 15, 2011 2:33 pmFollowed by: 21 members; Thanked: 158 times

by pemdas » Mon Dec 19, 2011 12:28 pm

once more
x and y are two jars
x/4=y/3 and 4y=3x. It's evident y is less than x. Therefore, (y/3+x/4)/x will give us right proportion. We need to substitute and plug in y=3x/4 -> (3x/12+x/4)/x=6x/12x=1/2

Success doesn't come overnight!

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