SOLUTION: A boat travels 25km/h in still water. If the boat goes upstream in a river flowing at a rate of 7km/h, for 2 km, and then returns downstream to its starting point, what is the aver

Algebra ->  Proportions -> SOLUTION: A boat travels 25km/h in still water. If the boat goes upstream in a river flowing at a rate of 7km/h, for 2 km, and then returns downstream to its starting point, what is the aver      Log On


   

Question 1126156: A boat travels 25km/h in still water. If the boat goes upstream in a river flowing at a rate of 7km/h, for 2 km, and then returns downstream to its starting point, what is the average speed for the while trip in km/h?
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
                   SPEED     TIME     DISTANCE
upstream          25-7=18    2/18         2        
downstream        25+7=32    2/32         2


Total Distance, 4 kilometers
Total Time, 1%2F9%2B1%2F16=25%2F%289%2A16%29

Average round trip speed,
%284%2A9%2A16%29%2F25=23.04
About 23 kilometers per hour