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A prior study estimated [tex]$\hat{p}$[/tex] as [tex]$34\%$[/tex]. The analysts would like to conduct a second study on the same topic with a margin of error, [tex]$E$[/tex], of 0.027 and a confidence level of [tex]$90\%$[/tex] ([tex]$z^\ \textless \ em\ \textgreater \ $[/tex]-score 1.645).

What is the minimum sample size that should be used so the estimate of [tex]$\hat{p}$[/tex] will be within the required margin of error of the population proportion?

[tex]\[ n = \hat{p}(1-\hat{p}) \cdot \left(\frac{z^\ \textless \ /em\ \textgreater \ }{E}\right)^2 \][/tex]

A. 17
B. 23
C. 430
D. 833


Sagot :

Given the parameters from the question, we need to determine the minimum sample size [tex]\( n \)[/tex] such that the estimate of [tex]\(\hat{p}\)[/tex] will be within the specified margin of error [tex]\((E)\)[/tex].

We are given:

- Sample proportion [tex]\(\hat{p} = 0.34\)[/tex]
- Margin of error [tex]\(E = 0.027\)[/tex]
- [tex]\(z^\)[/tex]-score corresponding to a 90% confidence level [tex]\(z^ = 1.645\)[/tex]

The formula to determine the minimum sample size is:

[tex]\[ n = \hat{p}(1 - \hat{p}) \left(\frac{z^}{E}\right)^2 \][/tex]

Now, substituting the given values into the formula:

1. [tex]\(\hat{p} = 0.34\)[/tex]
2. [tex]\(1 - \hat{p} = 1 - 0.34 = 0.66\)[/tex]
3. [tex]\(\frac{z^
}{E} = \frac{1.645}{0.027} \approx 60.926\)[/tex]

Next, calculate the expression inside the formula:

[tex]\[ \left(\frac{1.645}{0.027}\right)^2 \approx 3700.184 \][/tex]

Then, multiply by [tex]\(\hat{p}(1 - \hat{p})\)[/tex]:

[tex]\[ n = 0.34 \times 0.66 \times 3700.184 \approx 832.966 \][/tex]

Thus, the minimum sample size needed is approximately 833.

Therefore, the correct answer is:

[tex]\[ \boxed{833} \][/tex]