From banking collapse to DNA evidence: 'probability' revealed

MATHS WEEK:IF YOU really thought about your chances of winning the Lotto you most likely would not invest. So what are the chances?

The origins and application of probability, the mathematical response to uncertainty, was discussed in an engaging lecture yesterday by Dr Pádraig Kirwan, maths lecturer at Waterford Institute of Technology.

“Probability is a way to evaluate risk, get a grip on what we don’t know,” he told his audience of secondary school students at the Institute during the Maths Week event. The problem is, however, that we aren’t very good at it.

The banking collapse occurred because those managing risk did not see the dangers: “They didn’t estimate the risk properly.”

The rules of probability were developed in 1654 after French mathematicians Blaise Pascal and Pierre de Fermat exchanged letters discussing the toss of a coin and probability of certain results. The rules have changed little since.

The bankers failed to use probability properly, but lawyers defending OJ Simpson during his 1995 trial for the alleged murder of his ex-wife Nicole Brown Simpson and Ronald Goldman made good use of it, said Dr Kirwan. They argued that there were 12 million people in Los Angeles and possibly 12 people with matching DNA who might have accessed the crime scene, thus undermining the DNA evidence based of probability. The jury did not convict.

“Card Colm” Mulcahy talks about famous US mathematician and “sceptic” Martin Gardner tonight at 8pm in the Davenport Hotel. Gardner used maths to study claims of the paranormal.

Prof David Singmaster talks about the history of mathematical ideas tomorrow at 6pm in the Chester Beatty Library, Dublin Castle.

Maths week puzzle 3

The Persian polymath Omar Khayyam (1048 - 1131) is best remembered for his poetry, particularly the Rubaiyat of Omar Khayyam, but he was author of a maths book with possibly far more influence in the medieval world.

In his Treatise on Demonstration of Problems of Algebra, Khayyam gave the world a method for solving cubic equations.

These are equations where the unknown number is cubed. Readers may be more familiar with the quadratic equation, which takes its name from quadratus, the Latin for square.

The ancient Babylonians were able to solve quadratic equations. Why you may wonder?

Well to solve puzzles like the following. If you cant remember how to solve a quadratic equation, you may be able to figure it out anyway.

A group of friends have a gathering. Everybody is asked to bring a present for everyone else invited.

At the party four people dont show and there are 252 presents in total. How many people attended the party?

See mathsweek.ie/2012/irishtimesfor details for solving the problem