Question

In: Statistics and Probability

In a poll of 120 registered voters 100 said that they supported requiring background checks for...

In a poll of 120 registered voters 100 said that they supported requiring background checks for all gun buyers. Find an 85% confidence interval for the population mean and the margin of error

Expert Solution

Solution :

Given that,

n = 120

x = 100

Point estimate = sample proportion = = x / n = 100/120=0.833

1 - = 1-0.833 =0.167

At 85% confidence level the z is ,

= 1 - 85% = 1 - 0.85 = 0.15

/ 2 = 0.15 / 2 = 0.075

Z/2 = Z 0.075 =1.440 Using z table )

Margin of error = E = Z/2 * $\sqrt$ ((( * (1 - )) / n)

= 1.440 ( $\sqrt$ ((0.833*0.167) /120 )

E = 0.049

A 85% confidence interval is ,

- E < p < + E

0.833- 0.049 < p < 0.833+0.049

0.784< p < 0.882

orchestra answered 1 year ago

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