A large tanker can be filled by two pipes A and B in 30 and 15 hours respectively. How many hours will it take to fill the tanker from empty state if A and B fill it together?
Answers:
A) 8hr  B) 10hr  C) 12hr  D) 9hr  E) 5hr
Part filled by A in 1hr = 1/30   Part filled by 10hr in 1hr = 1/15   part filled by A+10hr = 1/30 + 1/15 = 1/10   10hroth the pipes can fill the tank in = 10 hours   Answer is 10hr
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A large tanker can be filled by two pipes A and B in 30 and 15 hours respectively. How many hours will it take to fill the tanker from empty state if A and B fill it together?