Question 1153673
The mean is 50/500 or 0.1
The SE is the sqrt ((p)*(1-p)/n) or sqrt(0.1*0.9/500)=0.0134
half-interval at 95% CI is 1.96*SE=0.0263
the 95% CI is (0.0737, 0.1263) or (7.37%, 12.63%)