# What is the difference between a z-test and a t-test?

What is the difference between a z-test and a t-test? When estimating population mean, how would you determine the optimal sample size when the maximum error limit is known; however, population variance is unknown and your initial sample size is less than 30? Provide a numerical example.

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What is the difference between a z-test and a t-test? When estimating population mean, how would you determine the optimal sample size when the maximum error limit is known; however, population variance is unknown and your initial sample size is less than 30? Provide a numerical example.

A z test is ...

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