A boat covers 154 km upstream in 7 hours and the boat covers 217 km in still water in 7 hours. Find the difference between the time taken by the boat to cover 240 km downstream and 110 km upstream?
A. 2 hours
B. 5 hours
C. 3 hours
D. 1 hour
E. None of these
Sol:
The upstream speed of the boat = 154/7 = 22
km/hr
The speed of the boat in still water = 217/7 = 31
km/hr
The speed of the stream = 31 – 22 = 9 km/hr
The downstream speed of the boat = 31 + 9 = 40
km/hr
The time taken by the boat to cover 240 km
downstream = 240/40 = 6 hours
The time taken by the boat to cover 110 km
upstream = 110/22 = 5 hours
Required difference = 6 – 5 = 1
