Probability Formula:
Or
$$\text{P(A)}\;=\;\frac{\text{n(E)}}{\text{n(S)}}$$
Where,
P(A) shows probability of an event.
n(E) shows number of favorable outcomes.
n(S) is the total number of events in the sample space.
Some Basic Probability Formulas
Suppose that the A and B are two events.
| Probability Range | 0 ≤ P(A) ≤ 1 |
| Addition | P(A∪B) = P(A) + P(B) – P(A∩B) |
| Complementary Events | P(A’) + P(A) = 1 |
| Disjoint Events | P(A∩B) = 0 |
| Independent Events | P(A∩B) = P(A) ⋅ P(B) |
| Conditional Probability | P(A | B) = P(A∩B) / P(B) |
| Bayes Formula | P(A | B) = P(B | A) ⋅ P(A) / P(B) |