Probability

Probability

1. "If an event can occur in "N" different mutually exclusive and equally likely ways, and if n of these have a characteristics e then the probability of occurrence is e is emual to n/N"

   • Addition and Multiplication Laws of Probability
     • Addition Law: Let A & B be two events in sample space S.
       • 1. If A & B are mutually exclusive events P(A U B)= P(A)+P(B) 2. If A & B are not mutually exclusive P(A U B)=P(A) + P(B) - P(A n B)
     • Multiplication Law: The probability of the intersection of two events is found using the multiplication law
       • 1. if A & B are independent events P(A n B)=P(A) P(B) 2. If A & B are dependent events P(A n B)=P(A) P(B I A)
   • Permutation
     • Choosing r of something that has n different types (order matters)
       • nPr= n!/(n-r)!
   • Combination
     • Ways to choose r different items out of n things to choose from, where order doesnt matter
       • nC r= n!/r!(n-r)! = (n/r)
   • Presenting Data
     • In probabilities one single problem can be presented and analysed using different tools, but you need to learn to choose the one that is most appropriate for each scenario.
       • Venn Diagram
       • Tree diagram
       • Results Table

2. RANDOM EXPERIMENT: Experiment where elements are selected arbitrarily RANDOM:Situation where any element has the same chance of being selected. SAMPLE SAPCE: Subset of a set of elementary events that occurs in the probability calculation. EVENT: Incident in whose realisation chance intervenes