In a river flowing at 2 km/hr, a boat travels 48 km upstream and then returns downstream to the starting point. If its speed in still water be 6 km/hr, find the total journey time.
Choose the correct answer: A) 10 hours B) 12 hours C) 14 hours D) 18 hours E) none of these

Rationale: "explanation : speed of the boat = 6 km / hr speed downstream = ( 6 + 2 ) = 8 km / hr speed upstream = ( 6 - 2 ) = 4 km / hr distance traveled downstream = distance traveled upstream = 48 km total time taken = time taken downstream + time taken upstream = ( 48 / 8 ) + ( 48 / 4 ) = 18 hr . answer : option d"
Answer: D