Question

Ritu can row downstream 20km in 2hours and upstream 4km in 2 hours.Find her speed of rowing in still water and the speed of the current

Answer 1

Answer:

Step-by-step explanation:

Let the speed of rowing in still water be X km/hr

Let the speed of rowing in current water be y km/hr

Downstream - (x+y)km/hr

Upstream - (x-y)km/hr

20/x+y=2 => 10/x+y=1 ->1

4/x-y = 2 =>2/x-y=1 ->2

X+y=10

X-y=2 (+)

2x=12

X=6

Substitute x=6 in 1

We get y= 4

Speed of rowing in Still water =6km/hr

Speed of rowing in current water =4km/hr

Hope you understand

Answer 2

Let speed of ritu in still water = x km/h

Speed of stream = y km/h

Then downstream speed of ritu = x + y

Upstream speed of ritu = x - y

According to question

20x+y=220x+y=2

=> x +y = 10 .... (1)

Also 

4x−y=24x−y=2

=> x - y = 2 ..... (2)

Add (1) and (2)

2x = 12 

=> x = 6

From (1), we get

6 + y = 10

=> y = 4

speed of ritu in still water = 6km/h

Speed of stream = 4km/h

Hope this helps you