Question 395683
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Hi
Note: The probability of x successes in n trials is: 
P = nCx* {{{p^x*q^(n-x)}}} where p and q are the probabilities of success and failure respectively. 
In this case p = .7 q =.3
nCx = {{{n!/(x!(n-x!))}}}
P(1 of 5 have had chicken pox) =  5(.7)^1(.3)^4 = .0284