Question

the speed of boat in still water is 15km/hr . It goes 30km upstream and return back at the same point in 4 hrs 30 mins . Find the speed of the stream

Answer 1

time=distance/speed

let x be the stream speed

relative speed at upstream= 15-x km/h(opposed)

relative speed at downstream= 15+x km/h(supported)

time needed for upstream= 30/(15-x) h

time needed for downstream= 30/(15+x) h

so,

4.5= {30/(15-x)}+{30/(15+x)}

solve it

and you will find x= 5km/h