Identical taps can fill a tank in 10 hours respectively. How many taps will be required to fill the tank in 4 hours in the presence of a leak that can empty full tank in 4 hours?

Question

Question

This question was previously asked in

RRB ALP Electrician 22 Jan 2019 Official Paper (Shift 3)

Answer 1

Given,

Inlet tap can fill the tank in = 10 hr

Leak can empty the full tank in = 4 hrs

Concept:/Formula:

Total work = Efficiency × Time taken

Calculation:

Let total work be LCM of (10, 4) = 20 units

Efficiency of each inlet pipe = 2 units

Efficiency of leak = 5 units

Let x inlet pipe are required to fill the tank in 4 hrs.

According to the question

⇒ 4 × [2x – 5] = 20

⇒ 2x – 5 = 20/4

⇒ 2x – 5 = 5

⇒ 2x = 10

⇒ x = 10/2

⇒ x = 5

∴ 5 inlet pipes are required to fill the tank.