A boat goes 40 km upstream in 8 hours and 36 km downstream in 6 hours. The speed of the boat in still water is :

Q. A boat goes 40 km upstream in 8 hours and 36 km downstream in 6 hours. The speed of the boat in still water is :
Answer: 5.5 km/hr
Notes: Speed upstream $latex = \frac{40}{8} = 5km/hr&s=1$ Speed downstream $latex = \frac{36}{6} = 6 km/hr&s=1$ ∴ Speed of boat in still water $latex = \frac{1}{2}(5+6) = 5.5 km/hr&s=1$ Hence option [B] is correct answer.