Two valves P and B can fill a sump in 37.5 minutes and 45 minutes respectively. Both valves are opened. The sump will be filled in just 30 minutes, if valve B is turned off after
A boy walking at the speed of 4 km/hr covers a certain distance in 6 hours 15 minutes. If he covers the same distance by cycle in 5 hours, then what is the speed (in km/hr) of the cycle?