A controversial bill is being debated in the state legislature. Representative Williams wants to estimate within 2 percentage points and with 95% confidence the difference in the proportion of her male and female constituents who favor the bill. What sample size should she obtain?

Respuesta :

Answer:

The sample size is  [tex]n = 2401[/tex]

Step-by-step explanation:

From the question we are told that

    The margin of  error is  [tex]E= 2\% = 0.02[/tex]

Given that the  confidence level is  95% then the level of significance is mathematically evaluated as

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

            [tex]\alpha = 5\% = 0.05[/tex]

The  critical value of [tex]\frac{\alpha }{2}[/tex]  obtained from the normal distribution table is   [tex]Z_{\frac{\alpha }{2} } = 1.96[/tex]  

Let assume that the sample proportion is  [tex]\r p = 0.5[/tex]

 Generally the sample size is evaluated as

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

            [tex]n = [\frac{1.96}{0.02} ]^2 * 0.5 ( 1- 0.5 )[/tex]

            [tex]n = 2401[/tex]