Any time that you calculate the chances of something happening or not happening, you are calculating a probability. Probabilities measure the likelihood of an event. Have you ever wondered what your chances are of being struck by lightning?
What are the chances of being struck by lightning in your lifetime? The probability of this happening is 1 in 3,000 or about 0.03%. You have a 0.03% chance of being struck by lightning in your lifetime. The probability is quite small, but it does exist. Be safe and mind Mother Nature!
See for yourself: http://www.youtube.com/watch?v=g3IroCiexL4
Check out the following interactive activity for more practice with probability.