Let me mention a problem which is so simple that it was included as an example in the revised Senior Mathematics syllabus in Queensland about 15 years ago.

All the elements heavier than iron were formed in supernovae explosions. Assuming that the two major isotopes of uranium, U-235 and U-238, were formed in equal amounts, use their present relativa abundances and their known half-lives to calculate how long ago the supernova explosion which formed these (prior to the formation of the solar system) took place.

The answer is about 6,000,000,000 years, which sits nicely between the age of the earth derived from independent calculations, and the 12 to 15 billion years for the age of the universe, derived from another lot of independent calculations.

Dr Ken Smith July 2006