Given that the probability of winning a game is 20%. The number of games won out of 20 follows binomial probability distribution.
The probability distribution/mass function is
[tex] P(X=x)=C(n,x)p^x(1-p)^{n-x},x=0,1,2,3,...,n [/tex]. Here [tex] n=20,p=0.2 [/tex]
The expected value of X is
[tex] E(X)=np=20*0.2=4 [/tex]
