A student is running a 3-kilometer race. He runs 1 kilometer every 2 minutes. Select the function that describes his distance from the finish line after x minutes.

Answer 1

I'd start with a quick sketch of the race, straight line will do, distance is 3km, and you are told the runner's pace is 1 km/2 minutes; or 0.5km/minute (since you want it in 1 unit of measure).

The distance from the finish line will be diminishing (total - how much the runner has run) so:

1. y = 3 - (0.5)(x) should do the trick! :-)

Answer 2

Her distance traveled is

0.5 km/min * x min

If we want to know how far from the finish line they are then subtract this value from 3 km.

3 - 0.5x = distance to finish line.

When x = 2

She is 2 km from the finish line.

when x = 6

she is 0 km from the finish line.