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Probability of an Event

There is a one in two chance of getting heads when a coin is tossed. When a coin is tossed you can get either a head or a tail. So there are 2 possible outcomes. But if we want heads then only 1 outcome is successful. So we want 1 outcome out of the 2 possible outcomes. We can write this as a fraction .

Every probability can be written as a fraction.
Remember: The smaller the fraction the less likely it is that the event will happen.

Example 1:
In lottery numbers, it is possible to work out that there are 13 983 816 ways to choose 6 numbers from 1 to 49. There is only one winning combination. What is the probability as a fraction?

To make a fraction you put the number of successful outcomes on top. That's a 1. Then put the total number of possible outcomes on the bottom. That's 13 983 816.
So the fraction is = 1 in 14 million. As this is a very small amount it is unlikely to happen.
Example 2: By looking at the statistics for accidents insurance companies work out a probability for them happening again. The probability of being killed in a plane crash has been found to be 11 million to 1, a very small probability.


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