ELI5: Explain Like I'm 5

Problem of points

Imagine you and your friend are playing a game where you roll a dice, and whoever gets a 6 first wins. But, what if you have to stop playing before someone wins? How do you decide who the winner is?

This is where the problem of points comes in. The problem of points is a mathematical problem that helps us determine how to fairly divide the prize when a game is stopped before someone wins.

To solve this problem, we first need to understand the probability of winning. In our example, both you and your friend have an equal chance of rolling a 6, so the probability of either of you winning is 1/6 or about 17%.

Next, we need to figure out how many rounds we need to play to have a high chance of someone winning. If we play just one round, the chance of someone winning is low. But, if we play multiple rounds, the probability of someone winning increases.

Let's say we agree to play 10 rounds. We can use probability formulas to figure out the chance of each of you winning at different points in the game. For example, after 5 rounds, the chance of someone winning is about 58%.

But, what if the game is stopped after 7 rounds with no winner? How do we decide who wins? This is where the problem of points formula comes in. We use the probability of winning at each point in the game to calculate a fair way of dividing the prize.

Thus, in our aforementioned example, we can use the probability formulas to calculate at what point one player is close enough to win as to make it fair to divide the prize offered in relation to the probability of winning. It is a way of deciding which player would have most likely to win, based on the probabilities that existed when the game had to be stopped.

Overall, the problem of points helps us determine a fair way to divide the prize when a game is stopped before someone wins, using probability calculations.