Q2. Formulate the following problems as a pair of equations, and hence find their solutions:
(i) Ritu can row downstream 20 km in 2 hours, and upstream 4 km in 2 hours. Find her speed of rowing in still water and the speed of the current.
Let the speed of Ritu in still water be x and speed of current be y,
Let's solve this problem by using relative motion concept,
the relative speed when they are going in the same direction (downstream)= x +y
the relative speed when they are going in the opposite direction (upstream)= x - y
Now, As we know,
Relative distance = Relative speed * time .
So, According to the question,
Now, Adding (1) and (2), we get
Putting this in (2)
Hence Speed of Ritu in still water is 6 km/hour and speed of the current is 4 km/hour