Two pipes, when working one at a time can fill a cistern in 2 hours and 3 hours, respectively while a third pipe can drain the cistern empty in 6 hours. All the three pipes were opened together when the cistern was 1/6 full. How long will it take for the cistern to be completely full?
- ((a))
1 hour
- ((b))
1 hour 20 minutes
- ((c))
1 hour 30 minutes
- ((d))
1 hour 15 minutes
Show Answer
1 hour





