Sailing with the current, a boat takes 3 hours to travel 48 miles. The return trip, against the current, takes 4 hours. Find the average speed of the boat for the entire trip and the speed of the current.

mishforever21
Dec 1, 2014

#1**+5 **

If it takes 3 hours to travel 48 miles with the current, the speed must have been 16 mph.

If it takes 4 hours to travel back against the current, the speed must have been 12 mph.

The average rate for the * whole* trip is just

(16 + 12) / 2 = 14 mph (this isn't technicallly correct, but we'll go with it !!!)

The speed of the current must have been 2 mph

Check......time with current x rate + time against current x rate = total distance

3(14 + 2) + 4(14-2) = 96 miles

CPhill
Dec 1, 2014

#1**+5 **

Best Answer

If it takes 3 hours to travel 48 miles with the current, the speed must have been 16 mph.

If it takes 4 hours to travel back against the current, the speed must have been 12 mph.

The average rate for the * whole* trip is just

(16 + 12) / 2 = 14 mph (this isn't technicallly correct, but we'll go with it !!!)

The speed of the current must have been 2 mph

Check......time with current x rate + time against current x rate = total distance

3(14 + 2) + 4(14-2) = 96 miles

CPhill
Dec 1, 2014