Question

The Turtle and Achilles compete. They start at the same time from the same place. Achilles runs at a speed of 13 mph while the Turtle moves at a speed of 1 mph. When Achilles reaches the finish line, the Turtle is 2/5 of a mile behind him. How much time did the competition take?

Answer 1

Answer:

2 minutes.  

Step-by-step explanation:

Let t be the time taken in competition and the distance covered by Achilles be x miles.

We have been given that when Achilles reaches the finish line, the Turtle is 2/5 of a mile behind him. This means that distance covered by turtle will be: $x-\frac{2}{5}$.

Achilles runs at a speed of 13 mph while the Turtle moves at a speed of 1 mph.

Since we know that $\text{Time}=\frac{\text{Distance}}{\text{Speed}}$, so we can set two equations for time taken by Achilles and turtle as:

$t=\frac{x}{13}...(1)$

$t=\frac{(x-\frac{2}{5})}{1}...(2)$

From equation (1) we will get,

$x=13t$

Upon substituting this value in equation (2) we will get,

$t=\frac{13t-\frac{2}{5}}{1}$    

Let us have a common denominator.  

$t=\frac{\frac{65t-2}{5}}{1}$

$t=\frac{65t-2}{5}$

Upon multiplying both sides of our equation by 5 we will get,

$5t=5\times \frac{65t-2}{5}$

$5t=65t-2$

$5t-65t=65t-65t-2$

$-60t=-2$

$t=\frac{-2}{-60}$

$t=\frac{1}{30}$

So, the competition took 1/30 hour, let us convert our given time in minutes.

$\frac{1}{30}\text{ hour}\times \frac{60\text{ minutes}}{\text{hour}}$

$\frac{1}{30}\times 60\text{ minutes}$

$2\text{ minutes}$  

Therefore, the competition took 2 minutes.