Question

16. A steamer goes downstream and covers the distance between two ports in 4 hours. It covers the same
distance upstream in 5 hours. If the speed of the stream is 2 km/h, find the speed of the steamer in
still water and the distance between the two ports.
[Hint: Speed upstream = speed in still water – speed of the stream]​

Answer 1

Answer:

let the distance be d km.

speed of boat or steamer be b km/h.

speed of stream be w km/h.

in downstream,

b+w=d/4

in upstream,

b-w=d/5

adding the two equations we get

2b=d/4+d/5

simplifying, 2b=9d/20,

b=9d/40.

subtracting the two equations we get

2w=d/4-d/5

2w=d/20

so d=40w.

given w=2km/h.

so d=40×2=80km.

and using d we get

b=9d/40= 9×80/40=18 km/h.

so, distance is 80km

and speed in still water is 18 km/h

b