Question

Pipe A can fill a tank in 25 hours while pipe B can empty it in 30 hours. They were operated on alternate hours starting with pipe A. Find the percentage of tank filled this way in 90 hours.​

Answer 1

Step-by-step explanation:

Pipe K can fill a tank in 25 hours while pipe L can empty the same tank in 20 hours.

Concepts used:

Time = Work/Efficiency

1 hour work of pipe = Work/Time

Calculation:

1 hour work of pipe K = 1/25

1 hour work of pipe L = -1/40

⇒ 1 hour work of pipe K and pipe L = 1/25 – 1/40 = 3/200

Time = Work/Efficiency

⇒ Time taken for tank to fill when pipes K and L work together = 3/4/3/200 hours = 50 hours

⇒ Time taken for one-fourth tank to fill by pipe G = 1/4/1/25 = 6.25 hours

⇒ Total time taken by pipes K and L in filling the tank = 50 + 6.25 hours = 56.25 hours

∴ Tank is filled in total time of 56.25 hours