Question 850137
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Hi,
Note: The probability of x successes in n trials is: 
P (x)= *[tex \large{{n}\choose{x}}] (p)^x(q)^(n-x) where p and q are the probabilities of success and failure respectively. 
In this case p(A wins) = .45 & q(A loses)  = .55    n = 4
 P(x= 2) = *[tex \large{{4}\choose{2}}](.45)^2(.55)^2
 P(x= 3) = *[tex \large{{4}\choose{3}}](.45)^3(.55)^1
 P(x= 4) = *[tex \large{{4}\choose{4}}](.45)^4(.55)^0   
P(x &#8805; 2)= P(x= 2) +  P(x= 3) +  P(x= 4)
0r using TI Calculator
p = .05,  n = 100
P(x &#8805; 2) = 1 – P(x &#8804; 1) = 1 -  binomcdf(4, .45, 1)