Question

Three pipes can empty a tank in 10 hrs. How many pipes are required to empty the tank in 2 hrs?
1. 18
2. 6
3. 10
4. 15

Answer 1

Correct Answer - Option 4 : 15

Given

3 pipes can empty a tank =10 hrs 

Formula used.         

Men₁ × Days₁ × efficiency₁/ Work₁ = Men2 × Days2 × efficiency2/ Work₂

Calculation 

3 pipes × 10 hours = (x + 3 pipes) × 2 hours 

⇒ 30 = 2x + 6 

⇒ 30 - 6 = 2x 

⇒ 24 = 2x

⇒ x = 12

The required pipes are 12 + 3 = 15

∴ The required answer is 15.