Pipe ‘A’ and pipe ‘B’, together can fill 40% of

Solution

Time taken by pipe ‘A’ and pipe ‘B’, together to fill the tank = 6/0.40 = 15 hours Let the total capacity of tank = 105units (LCM of 15 and 35) Efficiency of pipe (A + B) = 105/15 = 7 units/hour Efficiency of pipe ‘C’ = 105/35 = 3 units/hour Tank filled by pipe (A + B) in 28 hours = 12 × 7 = 84 units Time taken by all three pipes to fill the remaining tank = (105 – 84)/ (7 – 3) = 21/4 hrs. =.5.25hours Total time taken = 12 + 5.25 = 17.25 hours