Probability

The probability of an event (or something) happening is similar to the chances of it happening.

Common examples of probability are determined by: flipping a coin

rolling a die or dice

using a deck of playing cards

picking something out of a bag

Using probability, we can determine the number of possible outcomes and then

discover our chances out of the number of possible outcomes.

Here is a tree diagram illustrating the possible outcomes of flipping a coin three times in a row.

There are 8 possible outcomes

If we look at the probability of flipping a coin and then rolling a die...

... we can see that there are 12 possible outcomes

Using this example to express the probability of a coin flipping tails side up followed by and even number..

we would say the chances are 3 out of 12 (or simplified to a 1 in 4 chance).

Outcomes can be also be expressed as a fraction, such as: 3 simplified to 1

12 4

Further hints...

Probability can also be expressed with a position on a probability scale.

Examples: impossible unlikely unsure likely definitely

poor sub-par average above-par excellent

Probability can also be expressed using percentage

Example: a 1 in 4 chance is the same as a 25% chance

ONLINE TESTS

Test your knowledge of probability at

(there are three levels of difficulty to choose from)