Question 333028
1. compute the sample point estimate Pbar = 1143/86991 = 0.0131
2. compute the standard error:   {{{sqrt(pbar*(1-pbar)/n)=sqrt(0.0131*(1-0.0131)/86991)=0.000386}}}
3. Identify the critical value for 95% confidence:  Z=1.96
4. Compute the 95% confidence interval for {{{pi=population_proportion}}}
   pbar -\+ Z*Standard Error = 0.0131-1.96*0.000386, 0.0131+1.96*0.000386
   (0.0123, 0.0139)
==
Note:  This is a binomial distribution problem 
X = number testing positive~Binomial (n,p)=binomial(86991,0.0131)
But since the sample size is large and n*pbar=1143 exceeds 10
this meets the criteria for using the normal approximation to the Binomial. 
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This is needed since the Binomial is skewed in the extremes and these requirements limit the Binomial from the extremes, allowing the Normal approximation.