I'm trying to find as many golden tickets as I can, so that I can sell them to rich, spoilt kids that want to go on a tour of Wonka's chocolate factory.
Fortunately, I have a machine that can tell me the probability that a ticket is present within a chocolate bar without having to open it. I can use this machine on chocolate bars before I must buy them, so I can use it to select the chocolate bars most likely to have tickets.
Of course, the machine isn't accurate, so the probability it gives me will have some error, but this error will be normally distributed around the real probabilities, so it will even out across multiple chocolate bars. This means that if I tested every chocolate bar, I could determine the overall probability of finding a winning ticket by averaging the predictions produced by the machine.
So I test 10,000 chocolate bars (its Costco), and pick the 100 with the highest probabilities as predicted by the machine.
Now, to test the machine's accuracy, I average its predictions for these 10