Question

A man can row $9\frac{1}{3}$ kmph in still water and finds that it takes him thrice as much time to row up than as to row down the same distance in the river. Find the speed of the current in kmph.

• A. $2\frac{12}{7}$
• B. $4\frac{2}{3}$
• C. $2\frac{6}{5}$
• D. $4\frac{4}{9}$

Answer 1

The correct option is B $4\frac{2}{3}$

Let the speed upstream be x kmph Then speed downstream = 3x kmph
Speed in still water = $\frac{1}{2}$ (3x + x) kmph = 2x kmph
$\therefore$ 2x = $\frac{28}{3}$ $\Rightarrow x=\frac{14}{3}$
So Speed upstream = $\frac{14}{3}$ km/hr;
Speed downstream = 14 km/hr
Hence speed of the current = $\frac{1}{2}(14-\frac{14}{3})$ km/hr
=$\frac{14}{3}$ km/hr = $4\frac{2}{3}$ km/hr