Learning objectives
Describe how likely events are and calculate simple probabilities.
By the end of this course, you should be able to explain the key ideas, use the methods and answer practice questions.
Lesson notes
Likelihood
An event may be impossible, unlikely, even chance, likely or certain.
Probability scale
Probability ranges from 0 (impossible) to 1 (certain).
Simple probability
Probability = number of favourable outcomes ÷ total number of equally likely outcomes.
Example
A fair coin has two equally likely outcomes. The probability of heads is 1/2.
Worked example
A fair six-sided die has three even numbers (2, 4, 6). P(even) = 3/6 = 1/2.
Practice quiz
Enter an answer for each question. Then select Check answers. For fractions, use forms such as 1/2.