The 'birthday paradox' maths problem

The unexpected maths problem at work during the Women's World Cup Getty Images A surprising number of footballers at the recent women's World Cup shared the same birthday as someone else in their team If you are in a room with 22 other people, it’s more likely than not that two of them share a birthday. The problem is usually phrased along these lines: "How many people do you need to have at a gathering before the probability of at least two people sharing a birthday rises above 50%?" The large numbers of pairwise combinations thrown up by birthday-type problems are frequently the driving force which allows seemingly unlikely events to occur purely by chance In total I identified 24 pairs of birthdays within the teams, so the same "birthday reasoning" suggests that there is – more likely than not – a pair of pairs among these dates too. Getty Images World Cup players Simone Boye Sørensen, Luna Gevitz, Sandra Sepúlveda and Diana Ospina Garcia all share the same birthday - 3 March Based on this study and now doubting the uniqueness of DNA identifiers, lawyers across the US argued for similar comparisons to be made in other DNA databases, including the national DNA database containing 11 million samples.