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

Redeem

Might be really easy but couldn't figure it out

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 40
Joined: Wed Jan 13, 2010 7:17 pm
Thanked: 1 times
Followed by:1 members

Might be really easy but couldn't figure it out

by imane81 » Fri Jan 22, 2010 12:35 pm

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Thank for solving this one ..

When n liters of fuel was added to a tank that was already 1/3 full, the tank was filled to 7/9 of its capacity. In terms of n, what is the capacity of the tank, in liters?
A. 10/9n
B. 4/3n
C. 3/2n
D. 9/4n
E. 7/3n
Top
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 98
Joined: Mon Nov 23, 2009 2:30 pm
Thanked: 26 times
Followed by:1 members

by ace_gre » Fri Jan 22, 2010 1:07 pm
Hi, Here is my approach.

Say the capacity of tank is T.

n+ T/3 = 7T/9
n = 7T/9 - T/3
n= 4T/9
T = 9n/4

I am assuming that ns in the choices are in the numerator.
Top
User avatar
Legendary Member
Posts: 1560
Joined: Tue Nov 17, 2009 2:38 am
Thanked: 137 times
Followed by:5 members

by thephoenix » Fri Jan 22, 2010 10:14 pm
imane81 wrote:Thank for solving this one ..

When n liters of fuel was added to a tank that was already 1/3 full, the tank was filled to 7/9 of its capacity. In terms of n, what is the capacity of the tank, in liters?
A. 10/9n
B. 4/3n
C. 3/2n
D. 9/4n
E. 7/3n
eqn is (1/3)x+n=(7/9)x
solving for x=(9/4) n
Top
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Sat Jan 23, 2010 1:05 am
imane81 wrote:Thank for solving this one ..

When n liters of fuel was added to a tank that was already 1/3 full, the tank was filled to 7/9 of its capacity. In terms of n, what is the capacity of the tank, in liters?
A. 10/9n
B. 4/3n
C. 3/2n
D. 9/4n
E. 7/3n
This is an ideal situation for picking numbers if the algebra doesn't leap out at you.

We have 1/3 and 7/9, so let's set the capacity of the tank at 9 litres to keep the arithmetic simple.

We started at 1/3 full: that's 3 litres.
We ended at 7/9 full: that's 7 litres.

Therefore, we added 4 litres, i.e. n=4.

Since the question is asking for the capacity of the tank in terms of n, we want to pick the choice that gives us a value of 9 (the capacity of our tank) when we plug in n=4.

a) 40/9... bzzt
b) 16/3... bzzt
c) 12/2... bzzt
d) 36/4... ding ding - we have a winner!

Since all the choices are simple multiples of n, no need to check (e).
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top

GMAT/MBA Expert

User avatar
Elite Legendary Member
Posts: 10392
Joined: Sun Jun 23, 2013 6:38 pm
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:511 members
GMAT Score:800

by [email protected] » Tue Mar 13, 2018 7:04 pm
Hi All,

We're told that when N liters of fuel was added to a tank that was already 1/3 FULL, the tank was filled to 7/9 of its capacity. We're asked for the capacity of the tank, in terms of N, in liters. This question can be solved by TESTing VALUES.

Since the tank ends up 7/9 full, it would make sense to choose a value for the FULL TANK that is a multiple of 9. In this case, the easiest value would be 9 (note: this is NOT the value of N). We can now set up an equation and solve for N...

N + (1/3)(9) = (7/9)(9)
N + 3 = 7
N = 4

Thus, we're looking for an answer that equals 9 when N=4. There's only one answer that matches...

Final Answer: D

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Top
Post new topic Post Reply
• Page 1 of 1