Question

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 1

Answer :

Let, speed of Ritu in still water be x km/hr

and speed of current be y km/hr

Then speed downstream =(x+y) km/hr

speed upstream =(x−y) km/hr

we know, Time=

Speed

Distance

Then

x+y

20

=2 and

x−y

4

=2

⇒x+y=10 ...(1)

& x−y=2 ...(2)

adding both we get, 2x=12⇒x=6

Thus using (1) y=10−6=4

Hence the speed of Ritu in still water is 6 km/hr and the speed of the current is 4 km/hr.

Answer 2

Answer:

Speed of rowing in still water = 10 km/hour.

Speed of the current = 2 km/hour.

Explanation:

Speed of rowing in still water=( Ritu row downstream ( km/hour) ÷ 2 ) - (Ritu in upstream ( km/hour ) ÷2 )

= (20(km/hour)÷2) - ( 4 ( km/hour ) ÷ 2 )

= 10(km/hour)-2(km/ hour)

Speed of rowing in still water = 8km/hour.

Speed of current = Same as in still water

= 8km/hour.