How does the variance of the sample average, $\text{Var}(\bar{X}_n)$, change relative to the sample size ($n$)?

Answer

It shrinks proportionally to $1/n$.

When the underlying variables share a finite variance, $\sigma^2$, the variance of the sample average itself shrinks proportionally to $1/n$ as the number of trials increases.

How does the variance of the sample average, $\text{Var}(\bar{X}_n)$, change relative to the sample size ($n$)?
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