In late June 2012, Survey USA published results of a survey stating that 55% of the 579 randomly sampled Kansas residents planned to set off fireworks on July 4th. Determine the margin of error for the 55% point estimate using a 95% confidence level. The margin of error is: _____% (please round to the nearest percent)

Respuesta :

Answer:

The Margin of Error E [tex]\simeq[/tex] 4.1 %

Step-by-step explanation:

Given that:

The sample size = 579

The sample proportion [tex]\hat p = 55\%[/tex] = 0.55

From the confidence interval of 95%

The level of significance ∝ = 1 - C.I = 1 - 0.95 = 0.05

The critical value of [tex]Z_{\alpha/2 } = Z_{0.025} = 1.96[/tex]

Thus;

The Margin of Error E = [tex]Z_{\alpha/2 } \times \sqrt{{\dfrac {\hat p ( 1 - \hat p }{n}}[/tex]

The Margin of Error E = [tex]1.96 \times \sqrt{{\dfrac {0.55 ( 1 - 0.55) }{579}}[/tex]

The Margin of Error E = [tex]1.96 \times \sqrt{{\dfrac {0.55 ( 0.45 )}{579}}[/tex]

The Margin of Error E = [tex]1.96 \times \sqrt{{\dfrac {0.2475}{579}}[/tex]

The Margin of Error E = [tex]1.96 \times \sqrt{{4.2746114 \times 10^{-4}}[/tex]

The Margin of Error E = [tex]1.96 \times .020675[/tex]

The Margin of Error E = 0.040523

The Margin of Error E [tex]\simeq[/tex] 0.041

The Margin of Error E [tex]\simeq[/tex] 4.1%