Pipe A can fill an empty cistern in 4 hours while along with Pipe B it can fill it up in 3 hours. Only Pipe A is turned on for an hour after which Pipe B is also turned on. How much total time will it take to fill up the cistern?
1
3 hours 25 minutes
2
3 hours 15 minutes
3
3 hours
4
3 hours 20 minutes