__Category__: Mechanics, Physics"Published in Newark, California, USA"

Felix rode 18 miles downstream and back to the same place where he started, in 3 hours and 12 minutes. Find the rate of Felix in still water if the velocity of the stream is 3 miles per hour.

__Solution__:

To illustrate the problem, it is better to draw the figure as follows

Photo by Math Principles in Everyday Life |

Let s = be the distance traveled by Felix in upstream / downstream

v = be the velocity or speed of Felix in still water

v

_{1}= be the velocity in downstream

v

_{2}= be the velocity in upstream

t

_{1}= time traveled in downstream

t

_{2}= time traveled in upstream

If the word statement says "Felix rode 18 miles downstream and back to the same place where he started, in 3 hours and 12 minutes.", then the working equation is

Substitute the values of t

_{1}and t

_{2}so that we can solve for the value of v which is Felix' speed or velocity in still water.

By using quadratic formula, the value of v is

We need to choose the positive sign not the negative sign because the value of velocity will be negative which is not accepted as a final answer. Therefore, the velocity or speed of Felix in still water is