Question

A man swims 40 km downstream in 4 hours and the same distance upstream in 20 hours. Find the speed of the stream.
s: A.
B.
C.
D.
4 kmph
2 kmph
5 kmph
3 kmph​

Answer 1

Answer:

Step-by-step explanation:

Downstream:-

Speed of any body = ( speed of water flow + speed of body)

Upstream:-

Speed of any body = ( speed of body - speed of water flow )

Let the speed of man = X

Let the speed of water flow = Y

By using formula ,

 Speed = distance / time

Speed of man ( X+Y) in downstream = (40/4) = 10km/h

Speed of man (X-Y) in upstream = (40/20) = 2km/h

So,

     X + Y = 10     .......(i)

    X -  Y  = 2      .......(ii)

____________

 2X = 12

   X = 12/2

   X = 6

Putting the value of X= 6 in any equation.

X + Y = 10

Y = !0 - X

Y = 10 - 6

Y = 4

X = 6km/h is the actual speed of man.

Y = 4Km/h is the actual speed of water flow.

Therefore, option (A) 4km/h is correct option.

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