Solution:
Let the speed of stream be x km/hr
Given, speed of boat in still water is
So, speed of downstream
And, speed of upstream
Using, speed = distance/ time
Time taken by the boat to go
And, time taken by the boat to return
From the question, the boat returns to the same point in
∴
x
As the speed of the stream can never be negative, only the positive solution is considered.
Therefore, the speed of the stream is