Help:F.3 Maths

tommy26

ON a downstream trip, aman rows a boat for a distance of 66km in three hours; on an upstream trip, he rows the same distance in six hours. Find the speed of the current and the speed of the boat in still water rowed by the man

inthomaspy

Speed of the boat downstream = 66km / 3hr = 22 km/h
Speed of the boat upstream = 66km / 6hr = 11 km/h

Speed of the boat downstream = Speed of the boat rowed by the man in still water+Speed of water current
Speed of the boat upstream = Speed of the boat rowed by the man in still water-Speed of water current (As the motion of water current is against the rowing action by the man)

Hence, let speed of water current be x km/h and that of the boat rowed by the man in still water be y km/h
In the downstream journey, x + y = 22 ...(1)
In the upstream journey, y - x = 11 ...(2)

Solving (1) and (2), x = 5.5, y = 16.5