The speed of a ship in still water is 5 km/hr and the speed of the stream is 2 km/hr. Rohan rows to place at a distance of 21 km and comes back to the starting point. Find the total time taken by him.
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 10 hours.
Upstream speed = 5 - 2 = 3 km/h
Downstream speed = 5 + 2 = 7 km/h
⇒ Time taken during downstream = 21/7 = 3 hours
⇒ Time taken while going upstream = 21/3 = 7 hours
Total time = 10 hours