Speed of boat in still water is 7.5 km/hr and stream speed is 1.5 km/hr and is travelling upstream. It has a log of wood attached which decreases the speed of boat by 20%. Log of wood is detached somewhere in between and it comes back to the shore in 12 hours, Find the total time(in hour) for boat to reach other shore if total width in km is 55.
1
10(1/6)
2
9(5/6)
3
10 (1/3)
4
11(1/6)
5
None of these