Let E1, E2, E3, …………. En mutually exclusive and exhaustive events and A is dependent event occurs after E1, E2, E3, …………. En.
Probability of event A
By multiplication theorem
Where stands for probability of event A, if it is given that event already occurs.
|Example 1:||A bag contains 4 red and 3 black balls. A second bag contains 2 red and 4 black balls. One bag is selected at random. From the selected bag, one ball is drawn. Find the probability that the ball drawn is red.|
E1 : Selecting bag 1
E2 : Selecting bag 2
A : Drawing red ball