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Suppose that, as course instructor, you decide instead that you want to calculate a 95% confidence interval for the population proportion of all Cal Poly students who have ever marched in a Memorial Day Parade, and that you would like the margin of error of your 95% confidence interval to be .05, and that you would like to use a (most) conservative sample size for this task. What sample size should you use

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JeanaShupp

Answer: 385

Step-by-step explanation:

If prior population proportion p is unknown, then the formula to compute sample size will be:

[tex]n= 0.25(\frac{z^*}{E})^2[/tex]

where, E= Margin of error, z* = Critical zvalue

Given: E= 0.05

Critical value for 95% confidence = 1.96

Required sample size: [tex]n=0.25(\frac{1.96}{0.05})^2[/tex]

[tex]\\=384.16\approx385[/tex]

Hence, the required sample size = 385

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