Question

A river is flowing from east to west at a speed of 5 m/min. A man on south bank of river, capable of swimming 10m/min in still water, wants to swim across the river in shortest time. He should swim

• A. Due north
• B. Due north-east
• C. Due north-east with double the speed of river
• D. None of these

Answer 1

Answer: (A)

Due north

Answer 2

For shortest time, swimmer should swim along AB, so he will reach at point C due to the velocity of river.

i.e. he should swim due north