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Any event has a probability of occurrence between 0 and 100%, or zero to one. A probability of zero means the event will never occur, while a probability of one means the event is guaranteed to occur. Calculating probabilities requires that the data be unbiased, random, come from a representative sample, and use a valid sample size.

Probability event types may be simple or compound. Simple events cannot be broken down, while compound events are composed of two or more events. Compound events can be additive or multiplicative.

 Additive events are composed of independent events. Example: Two cars starting on a cold day, where each has a probability of starting of 0.90. What is the probability that at least one will start?– Probability = P(1) + P(2) P(12) = 0.90 + 0.90 (0.90 0.90) = (1.80 .89) =.91

 Multiplicative events are composed of dependent events One IC in a circuit has a probability of working of 0.99; another IC in a circuit has a probability of working of 0.90. What is the probability that the circuit will work?– Probability = P(1) P(2) = 0.99 0.90 = 0.89