The speed of a boat in still water is 12 km/h, and the speed of the stream is 3 km/h. A man goes to a place by boat, 45 km and comes back to the starting point. Find the total time taken by him.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 8 hours.
The speed of a boat in still water(x) is 12 km/h, and the speed of the stream(y) is 3 km/h
Downstream speed = x + y = 12 + 3 = 15 km/hr
Time = 45/15 = 3 hours
Upstream speed = x - y = 12 - 3 = 9 km/hr
Time = 45/9 = 5 hours
So,
Total time taken = 3 + 5 = 8 hours