Question

the speed of boat in still water is 12km/h and speed of stream is 2km/h. A distance of 8 km going upstream is covered in?

Answer 1

ANSWER = 2 hrs

Here you have to apply the concept of relative velocity

So, velocity of boat with respect to stream = velocity of boat - velocity of stream ( Vb - Vs ) = 12-8 = 4km/h

Now,

time = distance/ speed

= 8/4

= 2 hrs

Answer 2

Time = Distance/ speed . 8/12-2hr = 0.8hours or 48minutes