Question

A boat covers a certain distance downstream in 3 hrs and the same distance upstream in 5 hrs. If the speed of the boat in still water is 8km/hour, find the speed of the stream.

help me please I am struggling to solve this question​

Answer 1

The stream's speed is 2 km/hr. We don't need to know the distance.

Explanation:

Let the stream's speed = x

rate * time = d

The distance is the same going upstream as it is coming back down stream.

d_upstream = d_downsteam

(8 + stream)*3 = (8 - stream)*5

(8 + x)*3 = (8 - x)*5 Remove the brackets

24 + 3x = 40 - 5x Subtract 24 from both sides.

3x = 40 - 24 - 5x

3x = 16 - 5x Add 5x to both sides

3x + 5x = 16

8x = 16 Divide by 8

x = 16/8

x = 2