A boat's speed in still water is 4 km/h. The boat cruises from A to B along a river flowing at an average speed of x km/h in the direction A to B. If the distance AB is 5 km and the boat takes 2 hours more on its return journey, determine x. Hence, find the total time taken for the whole journey.
Answer: The speed of the boat in still water or 'b' = 10 km/h. The speed of the current or the river = 4 km/h. Therefore the speed of the boat when going upstream = b – r = 10 – 4 = 6 km/hr.
