Probability Formulas
Probability Formulas
Probability Formulas Useful in Competitive Exams
Probability questions are appearing in competitive exams , so a we are showing few formula on probability here. We will show more formulas ss and when needed.
This is because it will be more remindable in the exam if formulas are expressed with the concerned specific questions . Otherwise it becomes bit difficult to keep all in mind.
1. Probability Range for an event A
\[ = 0 = P(A) = 1 \]
2.Second formula- Rule of Complementary Events
\[ = P(A^c) + P(A) = 1 \]
3. Third formula – Rule of Addition for events A and B
\[ P(A or B) = P(A) + P(B) – P(A \cap B) \]
4. Disjoint Events
Events A and B are disjoint
\[ <=> P(A\cap B) = 0 \]
5. Conditional Probability i-e probability of event A subject to event B
\[ P(\frac{A}{B}) = \frac{P(A\cap B)} { P(B)} \]
6. Baye’s Formula is
\[ P(\frac{A}{B}) = P(\frac{B}{A})\times \frac{ P(A)}{ P(B)} \]
7. Independent Events
Events A and B are independent if and only if
\[ P(A\cap B) = P(A) \times P(B) \]
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