Special distributions for Quantitative R.V. Discrete R.V. Binomial Geometric Continuous. R.V. Uniform Normal PPF? CDF? E(X)?: Std(X)? P(X=K) = ? P(X<=K)=? shape: Skewness? Continuous R.V. PDF is meaningless. 1) PDF of continuous RV the height of the curve of corresponding point P(X=k)=0 2) the prob. of any given X=k, P(X=k) is Zero. Binomial (1) definition of X. number of trials that succeeded in n trials. Geometric. (1) definition of X. the order of first success in a series of trials. Binomial Setting difference. total number of trials n. E(X)=sum xipi. Std(X) = sqrt(sum(xi-mu_x)^2 pi). Binomial E(X)=Mu_x = np. Std(x) = Sigma_x = sqrt(np(1-p)). 当np>10且n(1-p)>10时. 当np<10且P>0. Geometric E(X)=Mu_x = 1/p. Std(x) = sqrt((1-p)/p^2). 永远. 当n(1-p)<=10且P->1时.