A man can row a boat in still water at the rate of 4 km/hr. He finds that it takes him twice as long to row upstream of a river as to row downstream of the same river, then the speed of the current of the river is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( \displaystyle\frac{4}{3}\ km/hr \)
Let the speed of the current be v km/hr. For the same distance, twice the time means half the speed, so the downstream speed is twice the upstream speed:
\( 4+v=2(4-v) \)
\( 3v=4 \)
\( \displaystyle v=\frac{4}{3}\ \text{km/hr} \)
CBSE Applied Mathematics (Class XII):
Boats and Streams
