1. Pipes P alone and Q alone can fill a tank in 20 hours and 24 hours respectively. They start filling the same tank on alternative hours, starting with P. Then, find in how many hours the tank will be filled completely?
3. Two pipes P and Q can separately fill a tank in 10 and 15 min respectively. A third pipe R can drain off 20 liters of water per minute. If all the pipes are opened, the tank can be filled in 10 min, then what is capacity of the tank? (In litres)
A) 100 B) 200 C) 300 D) 400 E) 500
4. Pipe P can fill a tank in 32 hours. While pipe Q can fill the same tank in 40 hours. Pipe R is an outlet pipe. When only pipes Q and R are open, the tank gets filled in 80 hours. In how many hours will the tank get filled, if only pipes P and R are open?
5. Time taken by pipes A, B and C together to fill a tank in 45 minutes and the time taken by pipes B and C together to fill the same tank is 75 minutes. If pipe B is 100% more efficient than pipe C, then find the time taken by pipes A & B together to fill the same tank?
7. Pipe P alone can fill a tank in 24 hours and can fill 75% of the tank in 10 hours along with Q. Pipe R can fill whole the tank along with Q in 12 hours. Find the time taken by pipe P, Q and R to fill 2/3 of the tank together?
A) 4.5 hrs B) 5 hrs 20 min C) 6 hrs D) 6.5 hrs E) 7 hrs 15 min
Explanation: P & Q can fill the 75% of tank in 10 hours, then P & Q can fill the 100% of tank in 40/3 hours
8. Pipe A takes x hours to fill the tank while pipe B takes 2x hours to fill the tank. Pipe C can empty the completely filled tank in 3x hours. All the pipes are opened together, for 6 hours. After that pipe B is closed and the remaining tank is filled in 12 hours. Find the time taken by pipes A and B together to fill the tank.
A) 28 hours B) 15 hours C) 21 hours D) 10 hours E) 5 hours
9. Two pipes P and Q can fill a tank in 30 minutes and 35 minutes respectively and a pipe R can empty that tank in 70 minutes. All three start their work and after sometime pipe R has been closed. If the total time taken to fill the tank from the beginning is 18 minutes, find after how many minutes R was closed?
A) 10 B) 18 C) 8 D) 11 E) 12
(7 + 6) × 18 − 3 × x = 210
3x = 24 ⇒ x = 8 minutes
After 8 minutes R was closed
Ans: C
10. Pipe A alone can fill a tank in 30 minutes and pipe B alone can fill the same tank in ‘X’ minutes. Pipe C (an empty pipe) alone can empty the tank in 60 minutes. If pipes A, B and C together take 180/7 minutes to fill the same tank, then find the time taken by pipe B alone to fill the 60% of the same tank?
A) 24 min B) 18 min C) 36 min D) 27 min E) 30 min
A + B + C = 7 ⇒ 6 + B − 3 = 7
B = 4
Efficiency of B = 4
Ans: D
11. Pipe A alone fills the tank in x hours and Pipe B alone fills the tank in (x − 8) hours. If the efficiency of pipe B is double that of pipe A and pipe A fills the tank is 50 liters per hour, then what is the capacity of the tank?
A) 400 liters B) 600 liters C) 780 liters D) 640 liters E) 800 liters
Explanation: x × 50 = (x − 8) × 100
x = 2x − 16
x = 16
tank capacity = 16 × 50 = 800 litres
Ans: E
