Question 1052951
P(flu) = .25,  n = 1000
Using the normal approximation of the binomial
mean = np = 250
sd = sqrt(npq) = sqrt(250*.75) = 13.693
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P(x<=260) 
z =  (260-250)/13.693 = 10/13.693 = .73
P(z<= .73) = .7673  0r 76.73%