The researcher decided to use a 95% confidence interval with a maximum error of 0.05 to estimate p, the proportion of old factory sites in the U. S. where toxic clean-up will be required before the sites can be reused. How large a sample does she need?

The sample size is    

Step-by-step explanation:

From the question we are told that

     The margin of error is

Here we will assume that the sample proportion is  

 From the question we are told the confidence level is  95% , hence the level of significance is    

=>  

Generally from the normal distribution table the critical value  of   is  

Generally the sample size is mathematically represented as  

=>        

=>    

easy math just plug in a and b

step-by-step explanation: