How do you find the mean variance, and standard deviation of the binomial distribution with #n= 70# and #p=.2#?

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Answer 1 · 2018-02-19T16:47:42

#E(X)=14#

#VAR(X)=11.2#

#sd=3.35(2dp)#

for a Binomial distribution

#X~B(n,p)#

mean, or expected value#" "E(X)=np#

variance #" "Var(X)=np(1-p)#

so in this case we have

#X~B(70,0.2)#

#:.E(X)=70xx0.2=14#

#Var(X)=70xx0.2xx0.8=11.2#

#sd=sqrt("Var(X)")=sqrt11.2=3.35(2dp)#