Question

Donna has 3 hours to spend training for an upcoming race. She completes her training by running full speed the distance of the race and walking back the same distance to cool down If she runs ata speed of 9 mph and walks back at a speed of 3 mph, how long should she plan to spend walking back?

Answer 1

Thomas, this is the solution:

Let d to be the distance of the upcoming race, therefore the equation would be as follows:

d/9 + d/3 = 3

Lowest Common Denominator = 9

d + 3d = 27

4d = 27

Dividing by 4 at both sides:

4d/4 = 27/4

d = 6.75

Therefore,

• Donna will run at full speed = 6.75/9 = 0.75 hours or 45 minutes

,

• Donna will walk to cool down = 6.75/3 = 2.25 hours or 2 hours 15 minutes.