a numerical measure of the likelihood that an event will occur; the ratio of the number or proportion of successes or favorable outcomes in the sample space to the number of outcomes in the sample space; the expected results (see also experimental probability); for example if a coin is flipped 50 times with 30 heads and 20 tails, the experimental probability of heads is 30/50 or .6; whereas, the theoretical probability for obtaining heads is 25/50 or 1/2 or .5

Probability that is determined on the basis of reasoning, not through experimentation.

the ratio of the number of favourable outcomes (what you want to happen) to the number of possible outcomes (what could happen)

A probability calculated from mathematical counting techniques.

Probability of an outcome occurring based on probability principles.

a measure of the likelihood that an event will occur; is equal to the ratio of favorable outcomes to the number of possible outcomes. For example knowing that there are six possible outcomes for rolling a fair number cube, one can assign the probability of 1/6 to each of the possible outcomes.

Ratio of the favorable outcomes for an event

The numerical measure of the likelihood that an event will happen; favourable outcomes ÷ possible outcomes.

The chances of events happening as determined by calculating results that would occur under ideal circumstances. For example, the theoretical probability of rolling a 4 on a four-sided die is 1/4 or 25%, because there is one chance in four to roll a 4, and under ideal circumstances one out of every four rolls would be a 4. Contrast with experimental probability.