Question

Ritu can row downstream 20 km in 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:

4 km/hr

Explanation:

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

Explanation:

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=SpeedDistance

Then x+y20=2 and x−y4=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.