Bartolo is running a race. He determines that if he runs at an average speed of 15 feet/second, he can finish the race in 6 seconds. If he runs at an average speed of 18 feet/second, he can finish the race in 5 seconds. Which equation represents this inverse variation?

For an inverse variation, one element increases while the other element decreases. In this question, the element or variable that increases is the speed while the element or variable that decreases is the time.

We can see from the question that

a) If he runs at an average speed of 15 feet/second, he can finish the race in 6 seconds.

b) If he runs at an average speed of 18 feet/second, he can finish the race in 5 seconds

Speed is inversely proportional to Time because the higher the speed, the lesser the time it takes to go or move in a particular direction or to go in a particular distance.

Hence, the Equation that represents these inverse variation is:

Speed is inversely proportional to Time

Speed (S) ∝ 1/ Time(T)

For inverse variation or proportionality, a constant is always needed

And the constant of variation or proportionality = Distance(D)

Therefore, Speed = Distance/ Time