A. 16 hours 24 mins
B. 14 hours 48 mins
C. 15 hours 36 mins
D. 13 hours 40 mins
E. None of these
Sol:
Total units = LCM (20, 30 and 40) = 120 units
Pipe A can fill = 6 units/hr
Pipe B can fill = 4 units/hr
Pipe C can empty = 3 units/hr
1 hour work = 6 + 4 – 3 = 7 units/hr
12 hour work = 7 * 12 = 84 units/hr
Remaining work = 120 – 84 = 36 units
Remaining tank can be filled by pipe A and B in,
= > 36 / (6 + 4) = 3 3/5 hour
Total time taken by fill the tank
= > 12 + 3 3/5 = 15 3/5 hour (or) = 15 hours 36 mins
