Q. 194.1( 29 Votes )
Pipe A can fill a cistern in 6 hours and pipe B can fill it in 8 hours. Both the pipes are opened and after two hours, pipe A is closed. How much time will B take to fill the remaining part of the tank?
Pipe A can fill the cistern in : 6 hours
Pipe B can fill the cistern in : 8 hours
Part of cistern filled by pipe A in one hour:
Part of cistern filled by pipe B in one hour:
Part of cistern filled by pipe A and pipe B together in one hour: =
They can fill the cistern together in hours.
Pipes A and B filled cistern together for 2 hours,
So part of the cistern filled pipes by A and B in 2 hours : =
Part of cistern which is empty =
Number of hours taken by pipe B to fill left over part of cistern : = ( here 8 is hours required by pipe B to fill the remaining part of the cistern).
Time taken by pipe B to fill the remaining part of the cistern: = = 3 hours 20 min
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