Two pipes, when working one at a time can fill a cistern in 2 hrs and 3 hrs, respectively while a third pipe can drain the cistern empty in 6 hrs. 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?
Krishna cycled a distance of 90 km at a certain speed. If he cycled 3 km slower every hour, he would have taken 5 more hours to reach his destination. What is the speed in kmph at which Krishna actually cycled?