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i need to prive that for a binomial r.v X E[X]=NP and VAR(X)=NP(1-P).

I tried to prove it using the deffinition of expectation:

E[x]=[tex]\sum xi \stackrel{N}{i} p^{i}(1-p)^{n-i}[/tex]

now what?

thanks...

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# Binomial density

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