Probability : Measurement of Quantity of uncertainity. Strength of our belief . Experiment must have outcome.Sample space is universal outcome. Tools for Probablity :a) Estimation (Risk)b) HypoTesting (Uncertainity)Risk is not equal to uncertainity. (No of tosses/rolls)(No of Posssible Outcome)Occurence of event is there when there is basic outcome of experiment.Trail means only once.variability1)Range(Distance)a. Absolute Range b. Inter Fractile Range :- That value of data set below or at which that data lies c. Inter Quartile Ranged. Quartile Deviatione. Coefficient Of Quartile Deviation2)Dispersion(Avg Deviation)3)Relative Dispersion(Coefficient of Deviation)201 253 104 633 57 500302 43 380 467 162 220Two Trail cane be experiment.Set of an event it is nothing but collection of elements.(Ex Class, Set of boys or girls in class)The no of elements can be infinite or zero.Venn Diagram : Schematic diagram of set There are five rules of probabilityRule of compliments p(A) = 1-p(A)'Rule of unions P(A?B) =P(A)+P(B)-P(A?B)Collectively Exhuastive Types of probablityObjective & SubjectiveAprior means knowing the answer without doing experiment.Conditional probablity = P(AinterB)/P(B)