For the final post of 2011 we wanted to leave you with a puzzle to solve as you take some time off to relax:

The “apple core” puzzle

Consider an apple of radius r. From the apple we remove the ‘core’ of height 2h. What volume of apple remains?

Please add your answers (and include your workings) as comments below. We’ll publish the answer in January.

Have a nice break and we’ll be back with fresh content in 2012 – but in the meantime, please check out the articles on here and the expert’s own blogs.