Question

ritu can row downstream 20km in 2 hrs and upstream 4km in 2 hrs. find the speed of rowing in still water and the speed of the current

Answer 1

Speed of boat in still water is 6km/h

Speed of current is 4km/h

Explanation:

We know speed = distance / time

Let the speed of boat in still water be x

Let the speed of current be y

Hence the speed of boat, down stream =
`x+y`

Distance downstream = 20km

Time taken = 2 hours

We have

`x+y=(20)/(2)`

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

Speed of boat upstream =
`x-y`

Distance upstream = 4

Time taken = 2

We have

`x-y=(4)/(2)`

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

Adding (1) & (2)

`2x=12`

`x=6`

Substituting in (1) we get

`y=4`