# Sarah bikes 15 miles in 70 minutes. Which is her average speed per minute?

Mar 16, 2016

0.21 $\frac{m i}{\min}$

#### Explanation:

When calculating average velocity, the following formula is applicable:

$\overline{v} = \frac{\Delta x}{\Delta t}$

Therefore,

$\overline{v} = \frac{\Delta x}{\Delta t}$

$\overline{v} = \frac{15 m i}{20 \min}$

$\overline{v} = 0.21 \frac{m i}{\min}$

It should be noted that this equation is only applicable to average velocity. Instantaneous velocity can only be obtained by integrating the $a \left(t\right)$ or taking the derivative of $x \left(t\right)$.