Question

A motor boat whose speed js 18km/hr in still water takes 1 hr more to go 24km/hr upstream to return downlstream to same spot .Find the speed of the stream

Answer 1

Let speed of stream be x km / hr

speed of boat in upstream = (18- x)km/hr

speed of boat in downstream = (18+x)km/hr

Time taken to travel 24 km in upstream = 24/ (18- x ) hr ( by using distance = speed * time)

Time taken by boat to travel 24 km in downstream = 24/ (18+x) hr

According to question

time taken to travel upstream - time taken to travel downstream = 1

24/ (18-x) - 24 / (18+x) =1

By solving

x = 6 km /hr

hope it helps........

Answer 2

Time=distance/speed

1=24/x-18

X-18=24

X=42km/hr