How to find the thermal expansion coefficient?

[da_coolest]

following is an example question i found on a lecture slide. I need some explanation to understand it.

http://img266.imageshack.us/img266/7062/thermal.png

Uploaded with ImageShack.us


In this example, Is it possible to get the thermal expansion coefficient from the data given in the question? if then, how to do that?

 

[Astronuc]

The thermal expansion coefficient α is given, α = 20 x 10^-6 °C^-1.