Posted by
**marie** on
.

A motor boat took 4 hours to make a downstream trip with a current of 3mph. The return trip against the same current took 8 hours. Find the speed of the boat in still water.

Call Y the boat's rate.

distance = rate x time.

downstream rate of boat is Y+3. t=4 hrs.

upstream rate of boat is Y - 3. t=8 hrs.

d(downstream) = (Y+3)4

d(upstream) = (Y-3)8

The distance is the same so set them equal to each other and solve for Y.

Thank you