Equal amounts of water - HELP - The Beat The GMAT Forum - Expert GMAT Help & MBA Admissions Advice

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

Redeem

Equal amounts of water - HELP

This topic has expert replies

Post new topic Post Reply

Previous Topic Next Topic

gmatpup: Senior | Next Rank: 100 Posts; Posts: 88; Joined: Sat Oct 15, 2011 6:38 pm; Thanked: 1 times; Followed by:1 members

Equal amounts of water - HELP

by gmatpup » Tue Jan 24, 2012 8:42 am

Please help! Thanks so much:)

Equal amounts of water were poured into two empty jars of different capacities, which made one jar 1/4 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 the greater capacity, what fraction of the larger jar will be filled with water?

A. 1/7
B. 2/7
C. 1/2
D. 7/12
E/ 2/3

Answer is [/spoiler]C[spoiler]

Please explain! Thanks again[/spoiler]

Quote

Source: Beat The GMAT — Problem Solving | Tue Jan 24, 2012 8:42 am

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

water

by pemdas » Tue Jan 24, 2012 9:25 am

double the amount of water in large jar, since the amounts of water are equal in both jars 1/4+1/4=1/2

gmatpup wrote:Please help! Thanks so much:)

Equal amounts of water were poured into two empty jars of different capacities, which made one jar 1/4 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 the greater capacity, what fraction of the larger jar will be filled with water?

A. 1/7
B. 2/7
C. 1/2
D. 7/12
E/ 2/3

Answer is [/spoiler]C[spoiler]

Please explain! Thanks again[/spoiler]

Success doesn't come overnight!

Quote

gmatpup: Senior | Next Rank: 100 Posts; Posts: 88; Joined: Sat Oct 15, 2011 6:38 pm; Thanked: 1 times; Followed by:1 members

by gmatpup » Tue Jan 24, 2012 9:33 am

but what about the 1/3?

Quote

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

by pemdas » Tue Jan 24, 2012 9:58 am

we need water not 1/3, the amounts are equal, if we pour into empty large jar one portion of water which makes 1/4 of the large jar, then additional portion of water (equal amount) will make another 1/4 added to it, 1/4+1/4=1/2

gmatpup wrote:but what about the 1/3?

Success doesn't come overnight!

Quote

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pm; Location: Vancouver, BC; Thanked: 5254 times; Followed by:1268 members; GMAT Score:770

by Brent@GMATPrepNow » Tue Jan 24, 2012 9:59 am

gmatpup wrote:Please help! Thanks so much:)

Equal amounts of water were poured into two empty jars of different capacities, which made one jar 1/4 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 the greater capacity, what fraction of the larger jar will be filled with water?

A. 1/7
B. 2/7
C. 1/2
D. 7/12
E/ 2/3

Answer is [/spoiler]C[spoiler]

Please explain! Thanks again[/spoiler]

The important point to note here is that equal volumes of water are poured into the two empty jars.

We then take the jar with the lesser capacity and pour its water into the jar with the greater capacity.

Which jar has the lesser capacity? The one that is 1/3 full or the one that is 1/4 full?

Well, since both jars currently hold the same volume of water, the one that is 1/3 full must have the lesser capacity.

So, we'll take the jar that is 1/3 full and pour its water into the jar that is 1/4 full.

Since both jars contain the same volume of water, this action will double the amount of water that was in the jar that is 1/4 full.

When we double the volume, that jar is now 1/2 full (1/4 + 1/4 = 1/2)

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Quote

sk8legend408: Senior | Next Rank: 100 Posts; Posts: 62; Joined: Fri Aug 12, 2011 12:37 am; Thanked: 3 times; Followed by:1 members

by sk8legend408 » Tue Jan 24, 2012 10:59 am

This is actually a simple problem if you pick numbers...

I picked 6 (liters or ounces) as the amount of water poured into each jar. The amounts each jar contain respectively are 6/24 and 6/18, or 1/4 and 1/3 respectively. The jar with less capacity, 6/18, is poured into the jar with more capacity, 6/24. (6+6)/24 = 12/24 = 1/2.

The answer is C.