SOLUTION: In the Summer, Rachel runs a taxi boat on a river to bring tourists to and from a waterfall which is 20km downstream from the boats port. There is an average current that flows at

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: In the Summer, Rachel runs a taxi boat on a river to bring tourists to and from a waterfall which is 20km downstream from the boats port. There is an average current that flows at       Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 860427: In the Summer, Rachel runs a taxi boat on a river to bring tourists to and from a waterfall which is 20km downstream from the boats port. There is an average current that flows at about 5km per hour towards the waterfall, so obviously the boat can travel fastest going towards the destination, and slower against the current coming back to the port. The boat has a certain speed that it can travel in still water. If Rachel needed to make the trip to and from the waterfall in 3 hours, what should the still water boat speed be? What would happen if the boat only had a still water boat speed of 5km per hour?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The current adds to the boat's speed in one
direction, and then subtracts from the boat's
speed in the opposite direction, so the
current has no net effect
-----------------------
Let +s+ = the boat's speed in still water
+20+%2B+20+=+s%2A3+
+3s+=+40+
+s+=+40%2F3+ km/hr
-------------------
+20+%2B+20+=+5t+
+5t+=+40+
+t+=+8+
If the boat's speed was 5 km/hr, it
would take 8 hrs to make the round trip