Let the speed of her rowing in still water be ‘a’ and speed of current be ‘b.’
We know, speed = \(\frac{distance}{time}\)
Relative speed of boat going upstream = a – b
Relative speed of boat going downstream = a + b
Given,
Ritu can row downstream 20 km in 2 hours, and upstream 4 km in 2 hours
⇒ a + b = 20/2 = 10 ---- (1)
and a – b = 4/2 = 2 ------ (2)
Adding eq1 and eq2
⇒ 2a = 12
⇒ a = 6 km/hr
Also,
b = a – 2 = 4 km/hr
Therefore,
Her speed of rowing in still water is 6 km/h and the speed of the current is 4 km/h
