Definition
Random experiment
A repeatable process whose exact outcome cannot be known with certainty beforehand.
What it means
You can describe what might happen, but you cannot know which result will happen on the next try. Repeating the process gives more trials of the same experiment.
Remember it
You know the menu, not the next choice.
Example
A bag contains one red tile, two blue tiles, and one green tile. Drawing one tile, recording its color, and replacing it is a random experiment because the possible colors are known but the next color is uncertain.
Watch for
A random experiment does not require all outcomes to be equally likely; the blue outcome in the example is more likely than red or green.
Common mix-up
Random means the next result is uncertain, not that every possible result has the same chance.
Exact meaning
A random experiment is a repeatable process with well-defined possible outcomes whose exact outcome cannot be predicted with certainty before a trial.