Question

please help its urgent ​

Answer 1

Given : -

Time taken while going down the stream = 6 hrs.

Time take for the same distance for  upstream = 7 hrs.

Speed of the stream (u) = 2 kmph.

Solution : -

Let the speed of the streamer be ' v '.

The distance he covered be ' D '.

when the streamer goes down the stream, the relative velocity of the streamer = v + u .

so, D = ( v + u ) x T

⇒ D = ( v + 2 ) x 6 _____ (1)

Now, when he goes upstream ,

the relative speed = ( v - u )

so, D = ( v - u ) x T

⇒ D = ( v - u ) x 7_____ (2)

equating the two equations 1 & 2 we get,

⇒ ( v - u ) x 7 = ( v + u ) x 6

⇒ 7v - 7u = 6v + 6u

⇒ v = 6u + 7u

⇒ v = 13u

⇒ v = 13 x 2

∴ v = 26 kmph

Therefore the speed of the streamer in still water (v) = 26 kmph