Question

A man swimming downstream overcome a float at a point $M$. After travelling distance $D$ he turned back and passed the float at a distance of $D/2$ from the point $M$, then the ratio of speed of swimmer with respect to still water to the speed of the river will be

• A. $2$
• B. $3$
• C. $4$
• D. $2.5$

Answer 1

Answer: (B)

Time taken by man to go from $M$ to $P$ and then $P$ to $N=$ time taken by float to go from $M$ to $N$.



$\frac{D}{v+u}+\frac{D}{2(v-u)}=\frac{D}{2u}$

Simplify to get $\frac{v}{u}=3$.