Question 615900
<font face="Times New Roman" size="+2">


I'm going to assume that you mean:  "A train goes 32 miles per hour for a certain distance and then turns around an goes 16 miles per hour for that same distance.  What is the average speed of the train."


You see how much nicer it is when you use correct English so that people who are trying to help you can understand what you want?


Let *[tex \Large d] represent the distance traveled at 32 miles per hour, then the amount of time required to travel this distance is *[tex \Large \frac{d}{32}] hours.  Likewise the amount of time required for the return trip is *[tex \Large \frac{d}{16}].  Therefore the time for the entire trip both ways is the sum of these two times:


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{d}{32}\ +\ \frac{d}{16}\ =\ \frac{3d}{32}]


The total distance traveled is *[tex \Large 2d], so the average speed is


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 2d\ \div\ \frac{3d}{32}\ =\ \frac{64}{3}\ =\ 21\frac{1}{3}] miles per hour.


<u>Super Double Plus Extra Credit</u>: Explain why, even though the average speed is 21 and one-third miles per hour, the average velocity is zero.


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
<div style="text-align:center"><a href="http://outcampaign.org/" target="_blank"><img src="http://cdn.cloudfiles.mosso.com/c116811/scarlet_A.png" border="0" alt="The Out Campaign: Scarlet Letter of Atheism" width="143" height="122" /></a></div>
</font>