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?

Respuesta :

Answer:

The sample size is  [tex]n = 384 [/tex]  

Step-by-step explanation:

From the question we are told that

     The margin of error is [tex]E = 0.05[/tex]

Here we will assume that the sample proportion is  [tex]\^ p = 0.5[/tex]

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

      [tex]\alpha = (100 - 95 ) \%[/tex]

=>   [tex]\alpha = 0.05[/tex]

Generally from the normal distribution table the critical value  of  [tex]\frac{\alpha }{2}[/tex] is  

   [tex]Z_{\frac{\alpha }{2} } =  1.96[/tex]

Generally the sample size is mathematically represented as  

    [tex]n = [\frac{Z_{\frac{\alpha }{2} }}{E} ]^2 * \^ p (1 - \^ p ) [/tex]

=> [tex]n = [\frac{1.96 }{0.05} ]^2 * 0.5 (1 - 0.5  ) [/tex]        

=> [tex]n = 384 [/tex]