Correct Answer - Option 3 : 2.4 hrs
Given:
Pipe X can fill the tank alone in 6 hr
Pipe Y can fill the tank alone in 4 hr
Concept:
Let, Pipe A can fill a tank in x hrs
⇒ Pipe A can fill a tank in 1 hr = 1/x
Calculation:
Pipe X can fill the tank in 1 hr = 1/6
Pipe Y can fill the tank in 1 hr = 1/4
⇒ Pipe (X + Y) can fill the tank in 1 hr together = (1/6) + (1/4) = (5/12)
⇒ Total time taken to fill the tank = 12/5 = 2.4 hr
∴ The required answer is 2.4 hours.