The CONFIDENCE.NORM function returns the confidence interval for a population mean, using a normal distribution. Your sample mean, x, is at the center of this range and
the range is x ± CONFIDENCE.NORM.

For example, if **x** is the sample mean of the length of major league baseball games, **x** ± CONFIDENCE.NORM is a range of population means. For any population mean, **μ0**, in this
range, the probability of obtaining a sample mean further from **μ0** than **x** is greater than alpha; for any population mean, **μ0**, not in this range, the
probability of obtaining a sample mean further from **μ0** than **x** is less than alpha. In other words, assume that we use **x**, standard_dev, and
size to construct a two-tailed test at significance level alpha of the hypothesis that the population mean is **μ0**. Then we will not reject
that hypothesis if **μ0** is in the confidence interval and will reject that hypothesis if **μ0** is not in the confidence interval. The confidence interval does not allow us to infer that there is
probability 1 – alpha that the next game will longer than time that is in the confidence interval.