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When we talk about probability we talk abut the likeliness of something to happen or for an event to occur. There are many instances where probability come into play but for many times we are able to highlight the occurrences with a simple math formula. All probability theory can be illustrated with a simple formula. Each time a formula is devised from an action we can assume the probability to increase. Take a look at some of the examples below.

In general:

Probability of an event happening = Number of ways it can happen
Total number of outcomes


Example: the chances of rolling a “4” with a die

Number of ways it can happen: 1 (there is only 1 face with a “4” on it)

Total number of outcomes: 6 (there are 6 faces altogether)

So the probability = 1

Example: there are 5 marbles in a bag: 4 are blue, and 1 is red. What is the probability that a blue marble will be picked?

Number of ways it can happen: 4 (there are 4 blues)

Total number of outcomes: 5 (there are 5 marbles in total)

So the probability = 4   = 0.8

While no event can be predicted with 100% accuracy, we strive to find a likeliness of an event to happen using the formulas above. When we add in an X-factor which is the random theory we can formulate that any of the above can become untrue by virtue of randomness. This is what makes probability so interesting. What is the likeliness of an event to occur is the question we attempt to answer.