A boat's speed in still water is 9 km/h, while stream’s speed is 1.5 km/h. A man rows to a location 105 km away and then returns to his starting position. The total time taken by him is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 24 hours.
Speed of the boat in still water = 9 km/h
Speed of the stream = 1.5 km/h
Distance = 105 km
Speed = Distance/Time
Hence,
Total time taken by the man:
= {105/(9 + 1.5)} + {105/(9 - 1.5)}
= 105/10.5 + 105/7.5
= 10 + 14
= 24 hours