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 boat be ‘a’ and speed of stream be ‘b.’
Speed = 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