A boat takes 6 hours to travel 36 km downstream and 12 hours to travel the same distance upstream. Find the speed of the boat in still water.
Show answer & explanation
Correct answer: A
Explanation
Speed downstream = 36 ÷ 6 = 6 km/h
Speed upstream = 36 ÷ 12 = 3 km/h
Speed in still water = (Speed downstream + Speed upstream) ÷ 2
= (6 + 3) ÷ 2
= 9 ÷ 2
= 4.5 km/h