Bunuel wrote:
Each of the three tanks holds n liters of water. After some amount of water is redistributed into the other two, the new ratio of water becomes 1:6:8 in terms of liters. What amount of water, in terms of n, were poured into the second tank?
A. n/15
B. 2n/15
C. n/5
D. 4n/15
E. n/3
Two approaches that I can think of
Approach 1 : Algebraic
Volume of water contained in three tanks = \(n + n + n = 3n\)
After distribution :
Assume that the common ratio is \(x\) is
Tank 1: Tank 2 : Tank 3 = \(x\) : \(6x\) : \(8x\)
\(x + 6x + 8x = 15x\)
As the volume remains the same among the three tanks
15x = 3n
n = 5x --- (1)
The initial volume of water in Tank 2 = \(n = 5x\)
The final volume of water in Tank 2 = \(6x \)
Volume of water poured = 6x - 5x = \(x\)
From (1)
\(x = \frac{n}{5}\)
Approach 2 : Assume Values
Assume that three tanks combined hold 15 gallons of water. Hence, each tank holds 15/3 = 5 gallons of water.
Hence, n = 5
After distribution Tank 2 hold 6 gallons of water.
Amount of water poured into tank 2 = 6 - 5 = 1 gallon
Amount of water poured in terms of n ⇒ \(\frac{n}{5}\)
Option C