The Mad River flows at a rate of 3 km/h. In order for a boat to travel 78.2 km upriver and then return in a total of 8 hr, how fast must the boat travel in still water?

what formula would be used to solve this problem?

2 answers

V = D/T would be the path to a solution.

Letting T = D/V, you know that

78.2/(V + 3) + 78.2/(V - 3) = 8 hr.

Solve for V, the speed of the boat in still water.
Is the answer 10 km/h?