Correct Answer - Option 2 : 40 hr
Given:
Three pipes A, B and C fills a tank in 4 hours. Pipe C can fill the tank at twice the speed of pipe B and pipe C can fill the tank at thrice the speed of pipe A
Calculation:
Let the time taken by pipe A to fill the tank be x hr
Time taken by B to fill the tank is x/3 hr
Time taken by C to fill the tank is x/6 hr
According to question,
(1/x) + (3/x) + (6/x) = 1/4
⇒ 10/x = 1/4
⇒ x = 40hrs
∴ Time pipe A will take to fill the tank is 40 hr.