Question

In a tank, there are two inlet pipes, pipe A and pipe B which can fill the empty tank in 15 and 12 hours respectively. If both the inlets are open for 5 hrs and after that only pipe B is open, Find the time taken by inlet B to fill the remaining tank.
1. 4 hrs
2. 5 hrs
3. 3 hrs
4. 2 hrs
5. 7 hrs

Answer 1

Correct Answer - Option 3 : 3 hrs

Given:

Pipe A and B can fill the entire tank in 15 hrs and 12 hrs respectively.

Calculation:

Let the capacity of the tank be 60x 

So, the efficiency of pipe A = 60x/15 = 4x

Efficiency of pipe B = 60x/12 = 5x

According to the question, Both the pipes are open for 5 hrs 

Tank filled in 5 hrs = 5 ( 4x + 5x) = 45x 

The remaining tank is filled by only pipe B 

⇒ Time taken = (60x – 45x)/5x

⇒ 3 hrs

∴ The time taken by inlet B to fill the remaining tank is 3 hrs