Olga’s swimming pool has three pipes connected to it. If the pool is e

Question

Olga’s swimming pool has three pipes connected to it. If the pool is empty, pipe A can fill it in 3 hours and pipe B can fill it in 4 hours. If the pool is at capacity, pipe C can empty it in 2 hours. The capacity of Olga’s pool is 2,400 cubic meters. If all three pipes are activated when the pool is empty, how many hours will it take for the pool to be filled to 60 percent of capacity?

A. 7.0

B. 7.2

C. 8.0

D. 8.6

E. 12.0

A. 7.0

B. 7.2

C. 8.0

D. 8.6

E. 12.0

yashikaaggarwal · Answer

The capacity of Olga’s pool is 2,400 cubic meters.

A Pipe can fill pool in 3 hours 
per hour capacity = 800 cubic meter

B Pipe can fill pool in 4 hours 
per hour capacity = 600 cubic meter

C Pipe can Empty pool in 2 hours 
per hour capacity = 1200 cubic meter

Per hour capacity of A, B and C = 800+600-1200 = 200 cubic meter

60% of 2400 = 1440 cubic meters

time taken by all 3 pipes = 1440/200 = 7.2 hours

answer is B

aviddd · Answer

Total volume = 2400 cubic meter

A can fill in 3 hours. A's rate = 2400/3 = 800 cubic meter per hour
B can fill in 4 hours. B's rate = 2400/4 = 600 cubic meter per hour
C can empty in 2 hours. C's rate = 2400/2 = 1200 cubic meter per hour

In one hour, volume filled = 800+600-1200 = 200 cubic meter.

60% of tank = 0.6 * 2400

200 cubic meter is filled in 1 hour. So, to fill 60% of tank, (0.6*2400)/200 = 7.2 hours

Answer: B

Mona2019 · Answer

the combined rate at which the water is filled into the pool is
Rate of A + Rate of B - Rate of C

let the capacity of the pool be x litres.
In 1 hr, A fills \(\frac{x}{3} litres\),
Similarly B fills \(\frac{x}{4} litres\) And C removes \(\frac{x}{2} litres \).

so rate at which the pool is being filled is :
\(\frac{x}{3}+\frac{x}{4}-\frac{x}{2} = \frac{x}{12} litres/hour\)

so x litre which is the full capacity of the pool is being filled in 12 hours.
so 0.6x (or 60% of the capacity) is filled in \(0.6*12 hours =7.2 hours.\)

Sorry , I am new to formatting here. Please bear with me ,m trying to learn. Thanks

kiranbhasker · Answer

Such questions are quite tricky if you don't read the question properly.
It is a very easy question but wasted nearly 10 mins, because i didnt read the question properly and considered pipe C as well to be filing the pool.

ScottTargetTestPrep · Answer

Solution:

We see that the filling rates of pipes A and B are 2,400/3 = 800 m^3/hr and 2,400/4 = 600 m^3/hr, respectively, while the emptying rate of pipe C is 2,400/2 = 1,200 m^3/hr. Therefore, their combined rate is 800 + 600 - 1,200 = 200 m^3/hr. Since this combined rate is positive, they fill the pool at 200 m^3/hr when all three pipes are activated.

Since 60 percent of the pool’s capacity is 0.6 x 2,400 = 1,440, it takes 1,440/200 = 7.2 hours to fill the pool to 60 percent of its capacity when all three pipes are activated.

Answer: B

Basshead · Answer

Please correct me if I'm wrong, but this question can be solved without knowing that the capacity of Olga's pool is 2,400 cubic meters.

Pipe A rate =  \frac{1}{3} 
Pipe B rate =  \frac{1}{4} 
Pipe C rate =  \frac{-1}{2}

Combined rate = 1/3 + 1/4 + (-1/2) = 1/12

Collectively will take 12 hours to fill the pool.

12 * 0.6 = 7.2

Answer is B.

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Olga’s swimming pool has three pipes connected to it. If the pool is e

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Olga’s swimming pool has three pipes connected to it. If the pool is e

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