Solve.
-A barge takes 6 hours to move (at a constant rate) downstream for 60 miles, helped by a current of 2 miles per hour. If the barge's engines are set at the same pace, find the time of its return trip against the current.
A) 8 hours
B) 6 hours
C) 120 hours
D) 10 hours

Question

Quizplus · Accepted Answer

The barge's speed in still water can be found by subtracting the current's speed from its effective speed downstream. Downstream speed = distance/time = 60 miles / 6 hours = 10 mph. Since the current contributes 2 mph, the barge's speed in still water is 10 mph - 2 mph = 8 mph. Against the current, its effective speed is 8 mph - 2 mph = 6 mph. To travel 60 miles upstream at 6 mph takes 60 miles / 6 mph = 10 hours.

Solve. -A Barge Takes 6 Hours to Move (At a Constant