GMAT Changed on April 16th - Read about the latest changes here

 It is currently 22 Apr 2018, 15:20

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# When 12 marbles are added to a rectangular aquarium, the water in the

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 44599
When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

20 Mar 2015, 07:18
Expert's post
1
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

84% (01:08) correct 16% (02:14) wrong based on 119 sessions

### HideShow timer Statistics

When 12 marbles are added to a rectangular aquarium, the water in the aquarium rises 1 1/2 inches. In total, how many marbles must be added to the aquarium to raise the water 2 3/4 inches?

A. 16
B. 18
C. 20
D. 22
E. 24

Kudos for a correct solution.
[Reveal] Spoiler: OA

_________________
Current Student
Joined: 23 May 2013
Posts: 189
Location: United States
Concentration: Technology, Healthcare
Schools: Stanford '19 (M)
GMAT 1: 760 Q49 V45
GPA: 3.5
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

20 Mar 2015, 08:38
1
KUDOS
We know that it takes 12 marbles to gain 1.5 inches. Now we need to find out how many marbles we need to gain 2.75 inches.

$$\frac{12 marbles}{1.5 inches} = \frac{x marbles}{2.75 inches}$$

$$x = \frac{12 * 2.75}{1.5} = \frac{12*\frac{11}{4}}{\frac{3}{2}} = \frac{3*11}{\frac{3}{2}} = \frac{33*2}{3} = 11*2 = 22.$$

Math Expert
Joined: 02 Aug 2009
Posts: 5774
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

20 Mar 2015, 09:08
1
KUDOS
Expert's post
Bunuel wrote:
When 12 marbles are added to a rectangular aquarium, the water in the aquarium rises 1 1/2 inches. In total, how many marbles must be added to the aquarium to raise the water 2 3/4 inches?

A. 16
B. 18
C. 20
D. 22
E. 24

Kudos for a correct solution.

apart from mathematical equation, the other way is by elimination and estimation...

12marbles-----1 1/2 in...... 24 marbles----3 in

12=4*3marbles-----1 1/2 in=1/2*3
4 marbles----1/2 in...
4*5 marbles----1/2*5=2 1/2..
so ans more than 20 and less than 24...

so ans 22 D..
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

GMAT online Tutor

Senior Manager
Joined: 02 Mar 2012
Posts: 344
Schools: Schulich '16
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

20 Mar 2015, 12:10
1
KUDOS
D

unitary method
3/2 inch is raised by 12 marbles

so 11/4 inch is raised by 12*(2/3)*(11/4)=22
Senior Manager
Joined: 28 Feb 2014
Posts: 295
Location: United States
Concentration: Strategy, General Management
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

20 Mar 2015, 20:41
Bunuel wrote:
When 12 marbles are added to a rectangular aquarium, the water in the aquarium rises 1 1/2 inches. In total, how many marbles must be added to the aquarium to raise the water 2 3/4 inches?

A. 16
B. 18
C. 20
D. 22
E. 24

Kudos for a correct solution.

use the ratio method
(12)/(3/2) = x/(11/4)
x=22

Director
Joined: 07 Aug 2011
Posts: 568
GMAT 1: 630 Q49 V27
When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

20 Mar 2015, 23:10
Bunuel wrote:
When 12 marbles are added to a rectangular aquarium, the water in the aquarium rises 1 1/2 inches. In total, how many marbles must be added to the aquarium to raise the water 2 3/4 inches?

A. 16
B. 18
C. 20
D. 22
E. 24

Kudos for a correct solution.

easy question for a kudo
As the aquarium is rectangular , the rise per marble will be same at each point.
so ,
$$\frac{12 * 2}{3} = \frac{4*X}{11}$$
_________________

Thanks,
Lucky

_______________________________________________________
Kindly press the to appreciate my post !!

Math Expert
Joined: 02 Sep 2009
Posts: 44599
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

23 Mar 2015, 05:27
Bunuel wrote:
When 12 marbles are added to a rectangular aquarium, the water in the aquarium rises 1 1/2 inches. In total, how many marbles must be added to the aquarium to raise the water 2 3/4 inches?

A. 16
B. 18
C. 20
D. 22
E. 24

Kudos for a correct solution.

MAGOOSH OFFICIAL SOLUTION:
Attachment:

Aqua_Marbles.png [ 20.21 KiB | Viewed 1983 times ]

_________________
SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1837
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

25 Mar 2015, 03:28

Marbles required $$= \frac{11}{4} * 12 * \frac{2}{3} = 22$$
_________________

Kindly press "+1 Kudos" to appreciate

Manager
Joined: 18 Dec 2014
Posts: 100
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

01 Apr 2015, 07:12
12 marbles = 1 1/2, 1 1/2 = 3/2

Raise to; 2 3/4 = 11 / 4

3/2 = 6/4

You need to go from 6 / 4 to 11 / 4, which is 5 / 4.

12 marbles = 6 / 4
2 marbles = 1 / 4

you need 5 / 4, 5*marbles is 10 marbles.

10 + 12 marbles = 22 marbles.
Non-Human User
Joined: 09 Sep 2013
Posts: 6649
Re: When 12 marbles are added to a rectangular aquarium, the water in the [#permalink]

### Show Tags

22 Dec 2017, 18:55
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: When 12 marbles are added to a rectangular aquarium, the water in the   [#permalink] 22 Dec 2017, 18:55
Display posts from previous: Sort by