Some of the games which are played over the holidays are based on skill, most however, are based on luck! But that doesn't mean you can't influence what happens! "Luck" is measured mathematically by probability and if you understand probability, you can make sure you stay lucky. Card games rely heavily on chance, and whether you win or not will depend on what cards you are dealt and what cards your opponents hold. Winning may depend on what the other players do, but you can increase your chances, and luck, by knowing what the mathematical probability of winning really is, when to take a risk and gamble, and when to play safe and fold early. The chances of winning the National Lottery are very small. There is one chance in 14 million that someone will win, but by buying two tickets the probability drops to one chance in 7 million. If you buy one ticket a week you can expect to win a jackpot sometime within 270,000 years! So as an investment, it’s not a good bet. Though of course it can be very exciting and the money does go to good causes!

	Use Bayesian Probability to dupe your friends
	This is a home-made game show that will certainly confuse your friends. You try to help them out but they won’t believe you’re helping them.
	You will need:
	Two potatoes Some chocolates (or other prize) Three boxes
	Place the two potatoes and the prize individually under the three boxes – only you, as quizmaster, should know what is under each box.
	Ask a friend to pick a box – they will win whatever is under the box. You get to eat the chocolates if they get a potato! But don’t show them anything yet.
	There will now be two unpicked boxes and under at least one of these unpicked boxes is a potato. As quizmaster, you now choose an unpicked box with a potato under it, and reveal the potato.
	There are now only two uncovered boxes: the one your friend has picked, and one other. The chocolates are under one of these boxes.
	Now you ask your friend, "Do you want to stick with the box you have already chosen, or change your mind and choose the other box?" You should try and encourage them to change their mind since at this stage, if your friend changes their mind they will have a higher chance of winning the chocolates. If they don't change their mind they have a higher chance of losing. BUT people almost always stick with their first choice. So in the long run, you will get to eat more chocolates than they will.
	Why?
	You may think that once we know which box hides one potato, the probability of winning the prize is one in two: we have two boxes, one hides a potato and the other the chocolates! Wrong – this game follows Bayesian probability! Keeping with their original box means that your friend’s chance of winning is actually one in three. Swapping boxes increases their chance of winning the chocolate to two in three.
	This all sounds terribly far fetched – but it really works. When your friend picks their first box, the chance of being right is 1 in 3. The probability of the chocolates being under one of the other boxes will be 2 in 3. When you lift one of the boxes to reveal a potato the probability of the chocolates being under the other box remains as 2 in 3. If your friend changes their mind they are more likely to win the chocolates - in fact they will win on average two times in every three games. If they don’t change they will win on average one time in every three games. But as quizmaster it is in your interest for your friends not to believe you are trying to help them so that you get to eat more chocolates!