Question

A man takes $2.2$ times as long to row a distance upstream as to row the same distance downstream. If he can row $55$ km downstream in $2$ hour $30$ minutes, what is the speed of the boat in the still water?

• A. $40$ km/hr
• B. $8$ km/hr
• C. $16$ km/hr
• D. $24$ km/hr

Answer 1

The correct option is C $16$ km/hr

Speed of the boat in downstream
$=\frac{55}{2.5}=\frac{55\times 10}{25}=22$ km/hr
Time taken to cover $55$ km in upstream $=2.5\times 2.2=5.5$ hr
Then, speed of the boat in upstream
$=\frac{55}{5.5}=10$ km/hr
$\therefore$ Speed of the boat in still water $=\frac{22+10}{2}=16$ km/hr