Question

Q.4 A boat goes upstream and covers the distance between two ports in 5
hours, while it covers the same distance downstream in 4 hours. If the
speed of the stream is 2 km/h, what is the speed of the boat in still water?

Answer 1

Answer:

18 kmph

Step-by-step explanation:

Distance between two ports be x.

Downstream Speed = u + v

Upstream Speed = u - v

where, u is speed of boat in still water and v is speed of the stream.

Time required for distance traveled in upstream Speed = 5

Time required for distance traveled in downstream Speed = 4

Distance covered in both cases is equal.

Distance = speed * time

Distance traveled in upstream = distance traveled in downstream

$5(u - v) = 4(u + v)$

the speed of the stream is 2 km/h,( given )

$u = 9v \: = 18 \: kmph$