Two pipes can fill the cistern in 18 and 12 hours respectively. A third pipe can empty it in 48 hours. If opened together, how much time will the pipes take to fill the cistern?
1
30 hours
2
10 hours
3
8.4 hours
4
14 hours
5
9.2 hours
Two pipes can fill the cistern in 18 and 12 hours respectively. A third pipe can empty it in 48 hours. If opened together, how much time will the pipes take to fill the cistern?