The respective ratio between the speed of the boat upstream and speed of the boat downstream is 2:3. What is the speed of the boat in still water if it covers 42 km downstream in 2 hours 20 minutes ? (in km/h)
Explanation:
Speed of boat downstream = 42/2+(20/60)=42/2+(1/3)
=42×3/6+1=42×3/7
=18 km/h
∴ Speed of boat upstream = 18×2/3= 12 km/h
∴ Speed of boat in still water
=Speed downstream+speed of boat upstream/2
=12+18/2=15 km/h