Answer: 700 (choice C)
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Explanation:
At 99% confidence, the z critical value is roughly z = 2.576 which is found using a Z table.
We're given that [tex]\hat{p} = 0.5[/tex] as the sample proportion and E = 0.05 is the desired error.
The min sample size n is:
[tex]n = \hat{p}*(1-\hat{p})\left(\frac{z}{E}\right)^2\\\\n \approx 0.5*(1-0.5)\left(\frac{2.576}{0.05}\right)^2\\\\n \approx 663.5776\\\\n \approx 664\\\\[/tex]
Always round up to the nearest integer.
Unfortunately n = 664 isn't one of the answer choices. The next closest value is 700. It appears that your teacher wants to know a valid sample size that is the smallest of the answer choices, not necessarily the smallest ever possible.
