SOLUTION: A boat traveled downstream a distance of 44 miles and then came right back. If the speed of the current was 5 mph and the total trip took 3 hours and 40 min, find the average speed

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: A boat traveled downstream a distance of 44 miles and then came right back. If the speed of the current was 5 mph and the total trip took 3 hours and 40 min, find the average speed      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 987652: A boat traveled downstream a distance of 44 miles and then came right back. If the speed of the current was 5 mph and the total trip took 3 hours and 40 min, find the average speed of the boat relative to the water.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
A boat traveled downstream a distance of d miles and then came right back. If the speed of the current was c mph and the total trip took t hours, find the average speed r of the boat relative to the water.

RT=D relates speed, time, and distance. 
                   speed     time    distance
DOWNSTREAM         r+c       ()       d
UPSTREAM           r-c       ()       d
Total                         t

                   speed     time       distance
DOWNSTREAM         r+c       d/(r+c)      d
UPSTREAM           r-c       d/(r-c)      d
Total                         t

d%2F%28r%2Bc%29%2Bd%2F%28r-c%29=t
Solve for r.

Evaluate according to system%28d=44%2Cc=5%2Ct=3%262%2F3%29.