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Sample Size for 95% Confidence

Problem (also attached):

1) An Entomologist wishes to estimate the average development time of the citrus red mite correct to within .5 day. From previous experiments it is known that standard deviation is in the neighborhood of 4 days. How large a sample should the entomologist take to be 95% confident of her estimate.


Solution Summary

This solution is provided in approximately 84 words in an attached .doc file. It uses an equation for margin of error to calculate sample size and provides a website to show how to calculate z-value.