Discussion Forum

A man takes 3 hours 45 minutes to row a boat 15 km downstream of a river and 2 hours 30 minutes to cover a distance of 5 km upstream. Find the speed of the river current in km/hr.

Answer:

Explanation:

Rate downstream $=\frac{15}{\left(3\frac{3}{4}\right)}$ km/hr

$=15\times\frac{4}{15}$ km/hr $=4$ km/hr.

Rate upstream $=\left(\frac{5}{2\frac{1}{2}}\right)$  km/hr

$=\left(5\times\frac{2}{5}\right)$ $=2$ km/hr

Speed of current $=\frac{1}{2}(4-2)$ km/hr = 1 km/hr.