Question

A fisherman rows 7500 m in 6750 seconds against the stream and returns in 75 minutes. Find the speed of the stream.

• A. 1 km/h
• B. 3 km/h
• C. 5 km/h
• D. 7 km/h

Answer 1

The correct option is A 1 km/h

Let the speed of the boat be = x km/h
Let the speed of the stream be = y km/h
Speed of the boat against the stream will be = (x - y) km/h
= $\left(\frac{7500}{6750}\right)\times \frac{18}{5}$ = 4 km/h ---(1)
Speed of the boat in the direction of the stream will be = (x + y) km/h
= $\frac{7500}{75\times 60}\times \frac{18}{5}$ = 6 km/h ---(2)
(1)+(2) → 2x = 10 km/h
Which means the speed of the stream = y = 1 km/hr