posted by Kgk .
Shoreline Travel operates a 3hr paddle boat cruise on the Missouri River. If the speed of the boat in still water is 12 mph, how far upriver can the pilot travel against a 5 mph current before it is time to turn around?
since time = distance/speed,
d/(12-5) + d/(12+5) = 3
now just solve for d. Assuming the round trip takes 3 hours.