Question

The latest poll of 400 randomly selected residents showed that 288 of them are hoping that the old town cinema stays open on Main Street.
With a desired confidence interval of 95%, which has a z*-score of 1.96, what is the approximate margin of error for this polling question?

A) 4%
B) 5%
C) 7%
D) 8%

Answer 1

The approximate margin of error is 4%.

Using the formula given and our information, we have:

$E=1.96\times \sqrt{\frac{\frac{288}{400}(1-\frac{288}{400})}{400}} \\ \\=1.96\times \sqrt{\frac{0.72(1-0.72)}{400}}=1.96\times \sqrt{\frac{0.72(0.28)}{400}} \\ \\=0.044\approx 0.04=4%$

Answer 2

Answer:

A

Step-by-step explanation: