**機率的運算法則**

- , .
- Law of Complement,
- Addition Law,
- 假如 , 則 , .

- 例
- Refer the previous monkeys example are selected from four by lottery. What is the probability that the selected monkeys are either of the same type or the same age?

so, and . And we are to calculate . To employ the addition law, we also need to calculate . And , so . Therefore,