Question

In a recent poll of 200 households, it was found that 152 had at least one...

In a recent poll of 200 households, it was found that 152 had at least one computer and one television. A 95% confidence interval to estimate the population proportion was calculated to be .701 to .819. What sample size would be needed to change the margin of error to .030?

Homework Answers

Answer #1

Solution :

Given that,

n = 200

x = 152

= x / n = 152 / 200 = 0.76

1 - = 1 - 0.76 = 0.24

Margin of error = E = 0.030

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96

Sample size = (  Z/2 / E)2 * * (1 - )

= (1.96 / 0.030)2 * 0.76 * 0.24

= 778.56 = 779

Sample size = n = 779

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