Question

A man can swim in still water at $9.6km/hr$, but takes twice as long to swim upstream then downstream. The speed of stream is

• A. $3.2km/hr$
• B. $2.3km/hr$
• C. $5.6km/hr$
• D. $6.5km/hr$

Answer 1

The correct option is A $3.2km/hr$

Speed of man is y $9.6km.hr$

let speed of stream is x km/hr

then, speed of down stream $-\left(9.6-x\right)km/hr$

Speed of upstream=$\left(9.6-x\right)km/hr$

As distance up stream same

$\begin{array}{c}9.6+x=\left(9.6-x\right)2\\ 9.6+x=19.2-9.6\\ x=\frac{9.6}{3}=3.2km/hr\end{array}$