Let E_{1}, E_{2}, E_{3}, …, E_{n} be n mutually exclusive events associated with a random experiment. If A is an event which occurs as a result of the events (cases) E_{1}, E_{2}, E_{3}, …, E_{n} then

\(P(\frac{Ei}{A})\) = Probability of occurrence of event A as a result of a particular cause (event) E_{i }

**\(\frac{P(E_i).P(A)}{\displaystyle\sum_{i=1}^n P(E_i).P(\frac{A}{E_i})}\)** **i = 1,2,..., n**