A boat takes 2 hours to travel 8 km and back in still water. If the velocity of water is 4 km/h, the time taken to go upstream 8 km and coming back is

Options

A. 2 hours 30 min
B. 2 hours 40 min
C. 2 hours 20 min
D. 2 hours 50 min

Answer

B

Explanation

Velocity of boat, `V_(B)`= 8km/hr, Velocity of water, `v_(w)`=4 km/hr
Time taken for going upstream, Time taken for going downstream Total time `t_(2)=(8)/(v_(B)+v_(w)) rarr 8/12 h`
total time =`t_(1)+t_(2)=2h` 40 min