probability formulas





Probability is the branch of mathematics which deals with the study of random phenomenons and probability of occurrence of events.

Some basic probability formulas are:

Notations use in Probability:

p(A) = probability of event A.

p(A \cup B) = probability of event A or B.

p(A \cap B) = probability of event A and B.

Probability Formulas:

1. Probability of an event “A” is:

p(A) = (Number of outcomes favorable to “A”) ÷ (Total numbers of outcomes)

2. For any two events “A” and “B” :

p(A \cup B) = p(A) + p(B) - p(A \cap B)

3. For any three events “A” , “B” and “C”:

p(A \cup B \cup C) = p(A) + p(B) + p(C) - p(A \cap B) - p(B \cap C) - p(C \cap A) + p(A \cap B \cap C)

4. For mutually exclusive events “A” , “B” and “C” ( or if p( A \cap B) = 0 and  p(A \cap B \cap C)= 0

 p(A \cup B) = p(A) + p(B)

and

 p(A \cup B \cup C) = p(A) + p(B) + p(C)

5. For two independent events “A” and “B”:

 p(A \cup B) = p(A) \times p(B)

and

 p(A \cup B \cup C) = p(A) \times p(B) \times p(c)

6. If A^| is the event complimentary to “A” then:

 p(A^|) = 1 - p(A)

7. If the occurrence of event “A” is dependent on the occurrence of event “B” then:

 p(A \cap B) = p(B) \times  p\left(\frac{A}{B}\right)



Related posts:

  1. Set Theory formulas Set Theory is a branch of mathematics which deals with...
  2. Algebraic Formulas Algebra is one of the most basic part of mathematics...
  3. Simple Interest formulas Interest is a type of fee paid for assets and...
  4. Ratio and Proportion Formulas As you know Ratio is a relation between two quantities...
  5. Compound Interest Formulas Compound Interest is a method of determining the interest or...