A boat moves at 5m/s in still water crosses a river without drift in 2min.if the width of the river is 480m then the river flows with a speed of?

Question

A boat moves at 5m/s in still water crosses a river without drift in 2min.if the width of the river is 480m then the river  flows with a speed of?

anonymous · Answer

@hartnn

hartnn · Answer

ok, so u have total distance travelled = 480 m , total time taken = 2 min
speed = ?

anonymous · Answer

480/120 = 4m/s

hartnn · Answer

but boat took 5 m/s , so river opposes it with 1m/s speed

mayankdevnani · Answer

Five meters per second for 2 minutes means the board has covered a distance of 600 m. 
|dw:1351161338249:dw|
Find out the other side of the triangle.  That'll give you the distance traveled by the water in the river.  Divide this distance by 120 seconds.  This gives you the speed up the river.