Probability

Probability is the chance that an event will occur given as a mathematic ratio that states the number of possible events giving one outcome in relation to a total number of similarly possible events in all outcomes. This ratio is often used in gambling to determine the odds, or the degrees of advantage or disadvantage in a competition based on previous results.

According to Leonard McCoy, in 2267, the chances of contracting Sakuro's Disease are literally billions to one. 

In 2269, Spock determined the probability of the Insectoid pod ship being dead at being .997 accurate. 

After succumbing to rapid aging, caused by Taurean headbands, Spock hypothesized that there was a possibility that the transporter could be used to restore the landing party to their original ages. Unfortunately, at the time, the odds were against the aged crewmembers 99.7-to-1. 

Later that year, Spock determined the probability of Harry Mudd being found on the planet Motherlode to be 81% ± .53, which was, in his words saying: "Mudd is probably there." 

Later yet that year, Spock determined the probability of approximately 82.5% that one of the members of the Vedala search party, assigned to find the Soul of the Skorr, was an saboteur. 

In a tactical projection of possible future Romulan deployments along the Romulan Neutral Zone, Data determined that their ships were deployed to support a policy of confrontation designed to test Federation defenses along the Neutral Zone. With this analysis, he projected a 90% probability that they would continue to pursue this policy. 

In 2370, an alien visiting Deep Space 9 named Cos introduced a gambling machine to Martus Mazur that was able to manipulate the laws of probability. Jadzia Dax later discovered this abnormality when she observed that the spin of over 80% of the solar neutrinos in the space station were spinning clockwise, when the given probability was that about 50% of should be spinning clockwise and the other 50% spinning counterclockwise. 

During the opening months of the Dominion War, Julian Bashir calculated his shipmates having a 32.7% chance of surviving the war.