Pipe A can fill an empty cistern in 6 hours and pipe B can fill the same empty cistern in 8 hours. Both the pipes are opened simultaneously but after two hours, pipe A is closed. How many hours will B take to fill the remaining part of the cistern?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. .
Given:
Pipe A can fill an empty cistern in 6 hours
Pipe B can fill the same empty cistern in 8 hours.
Both the pipes are opened simultaneously but after two hours, pipe A is closed
Calculations:
Total capacity (LCM of 6 and 8) = 24 units
Efficiency of A (24/6) = 4 units
Efficiency of B (24/8) = 3 units
Total efficiency of A and B = 7 units
Pipe A and B are opened for 2 hours = 7 × 2 = 14 units
Remaining capacity = 24 - 14 = 10 units
Time taken by B = 10/3 = hours