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
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Might be really easy but couldn't figure it out
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thephoenix
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eqn is (1/3)x+n=(7/9)ximane81 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
solving for x=(9/4) n
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Stuart@KaplanGMAT
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This is an ideal situation for picking numbers if the algebra doesn't leap out at you.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
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).
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
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[email protected]
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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
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
