theoretical & experimental probability

Theoretical probability is the probability of an event occurring based on theory, or proven mathematics.

Think of it as what 'should happen'.

eg When I roll a six-sided fair die, the theoretical probability of getting a 4 is 1 out of 6.

This is because there are 6 numbers on the die and each number should come up equally likely.

Experimental probability is the probability of an event occurring based from an experiment.

Think of it as what 'actually happened'.

eg When I roll a six-sided fair die 600 times, the number of 4's that came up was 88.

This means the experimental probability of getting a 4 from this experiment is 88 out of 600.