A small boat traveling 5 miles upstream, later back downstream for 1 hour and 40 minutes. The stream current is 4 mph. What is the velocity when it is in still water? Click to Show/Hide Solution $\text{1 hour and 40 minutes = 1.67 hours}$ \[ t_u + t_d = 1.67 \] \[ \frac{5}{V - 4} + \frac{5}{V + 4} = 1.67 \] \[ V = 2 \leftarrow \text{answer} \]
