Check out some similar questions!

monro · Sep 23, 2010, 04:21 PM

Suppose that you have a goal of driving two miles at an average rate of 60 mph. During the first mile you drive 30 miles an hour. How fast do you have to drive the second hour to maintain the 60 mph average?

galactus · Sep 23, 2010, 04:45 PM

If $x_{1}$ and $x_{2}$ are the distances covered at velocities $v_{1}$ and $v_{2}$ , then the average velocity over the whole trip is

$v=\frac{x_{1}+x_{2}}{\frac{x_{1}}{v_{1}}+\frac{x_{ 2}}{v_{2}}}$

In this case, you are given

$x_{1}=x_{2}=1$ ,

$v_{1}=30$ , and the final being v=60.

So, $v=\frac{1+1}{\frac{1}{30}+\frac{1}{v_{2}}}=60$

The thing is, $v\to {60}$ as $v_{2}\to {\infty}$

monro · Sep 23, 2010, 06:26 PM

So are you saying that it is an infinite solution, or that it is 60 mph?

galactus · Sep 24, 2010, 05:24 AM

In order to achieve 60 mph, you must travel at infinite velocity.

Warp 10. :)