Question

A cistern has two pipes one can fill it with water in 16 hours and other can empty it in 10 hours. In how many hours will the cistern be emptied if both the pipes are opened together when 3/5th of the cistern is already filled with water?

A 14 hours Correct Answer Incorrect Answer
B 18 hours Correct Answer Incorrect Answer
C 16 hours Correct Answer Incorrect Answer
D 20 hours Correct Answer Incorrect Answer

Solution

If both pipes are open, then total units per hour empty the tank (A-B) = 5-8 = -3 units According to question, Tank has 3/5 of its total capacity in the beginning 3/5 × 80= 48 units Time taken to empty the tank = 48/(-3) = 16 hours.

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