Ritu can row downstream 20 km in 2 hours, and upstream 4 km in 2 hours

1.	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.
Answer» 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

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.

Answer»

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