With the Six Nations Rugby Championship starting tomorrow, we have a puzzle about birthdays. And what, we hear you shout, have birthdays got to do with rugby? Well, it’s a little tenuous, but bear with us – it concerns the probability of members of a group sharing a birthday, and rugby union teams and squads give a very good illustration of this.
First of all think about how many people there need to be in a group for the probability of at least two people sharing a birthday to be greater than 50%. Or put another way how big does the group have to be before you will wager your hard-earned cash on two or more people sharing a birthday.
Working our way through the team and squad sizes . . .
Do you place a bet on a single rugby union team of 15 people?
What about the match-day squad of the 15 players and eight substitutes – 23 in all?
Maybe you are tempted by the combined starting fifteens of 30 players?
Or perhaps the combined match-day squads of 46 players.
Last offer – the two squads and the four match officials (referee, two assistant referees and the imaginatively named fourth official, a total of 50 individuals.
Still not placed a bet? Then, as we asked before, how many people would you need before opening your wallet?
We’ll give the answer and explanation on Monday morning at 9.00 as usual.