Question

A boat takes 19 hours for travelling downstream from point A to point B and coming back to point C midway between A and B.If the velocity of the stream is 4kmph and the speed of the boat in still water is 14kmph what is the distance between A and B.

Answer 1

Speed down stream $=(14+4)$ km/hr $=18$ km/hr

Speed up stream $=(14-4)$ km/hr $=10$ km/hr.

Let the distance between $A$ and $B$ be $x$ km.

Then, $\frac{x}{18}+\frac{\left(x/2\right)}{10}=19$

$\Rightarrow \frac{x}{18}+\frac{x}{20}=19$

$\Rightarrow \frac{19x}{180}=19$

$x=180$ km.