


Let the velocity of man be v and velocity of stream be u; Relative velocity downstream = u+v ; Relative velocity upstream = v-u
Let the distance covered be x in a time T1 downstream at a velocity v+u
In the upstream with relative velocity u-v, let the time taken to cover the same distance covered x be T2
Time = Distance / Speed
Hence, T1 = x / u+v and , T2 = x / v-u
Dividing T1 and T2 we get , T1 / T2 = x / v+u divided by x / v-u = v+u / v-u
NOTE: The answer is not root over (v+u / v-u) but (v+u / v-u)
