For example, suppose you wanted to know the probability that the S&P 500 would return a positive percentage this year, given initial gross domestic product (GDP) figures.

For example, 'I predict that there is a 50% chance of rain tomorrow'. ... How mathematics can give a probability or likelihood answer to events that are not certain in a mathematical way.

This doesn’t mean that I can put any old numbers on my thoughts — I would be proved a poor probability assessor if I claimed with 99.9% certainty that I can fly off my roof, for example.

A mysterious math problem from Science Buddies. If you survey a random group of just 23 people there is actually about a 50–50 chance that two of them will have the same birthday.

Probability of events, discrete and continuous random variables cumulative distribution, moment generatory functions, chi-square distribution, density functions, distributions. Introduction to ...