Question

The Bureau of Alcohol, Tobacco, and Firearms (BATF) has been concerned about lead levels in California wines. In a previous testing of wine specimens, the standard deviation of the lead levels was around 162 parts per billion. How many wine specimens should be tested if the BATF wishes to estimate the mean lead level for California wines to within 10 parts per billion with 95% confidence? You may use the previous study’s standard deviation for ? when performing your sample size calculation.

Answer 1

The following information has been provided:

The critical value for the significance level α=0.05 is Zc​=1.960. The following formula is used to compute the minimum sample size required to estimate the population mean within the required margin of error:

Therefore, the sample size needed to satisfy the condition , and it must be an integer number, we conclude that the minimum required sample size is

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