### 6.3. Confidence Interval Estimate for The Mean (σ Unknown)

The most common confidence interval estimate involves estimating the mean of a population. In virtually all cases, the population mean is estimated from sample data in which only the sample mean and sample standard deviation are available, not the standard deviation of the population. For this situation, statisticians [see Reference 1] have developed a sampling distribution called the t distribution to construct a confidence interval estimate of the mean. The confidence interval estimate for the mean is illustrated in the following example.

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