Question 522952
The formula to calculate a minimum sample size is as follows:
n = [z*s/E]^2

Where n is the sample size, z is the z value for the level of confidence chosen, s is the estimated standard deviation and E is the allowable error.

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a. Using this formula calculate the minimum sample size for a study when the level of confidence is 95 percent, the standard deviation is \$1000 and the allowable error is \$100. What actual sample size might you suggest? Explain your answer.
n = [1.96*1000/100]^2 = 385 when rounded up
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b. How large of a sample size would be needed for a 99 percent level of confidence? What actual sample size might you suggest? Why is this sample size larger? Explain your answer
n = [2.5758*1000/100]^2 = 664
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You need more "information" to have more confidence in the result.
A larger sample provides that additional "information".
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Cheers,
Stan H.
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