Chapter 9 Problem 2
Let $ X_k, 1 k n $ be a sequeunce of independent random variables, all with mean 0 and variance 1. Let \(S_n, S_n^*\), and \(A_n\) be their sum, standardized sum, and average, respectively. Below, we verify that \[
S_n^* = \frac{S_n}{\sqrt n} = \sqrt n A_n \implies \\
S_n = n A_n = S_n^*\sqrt n \implies \\
A_n = \frac{S_n}{n}
\] Which is true by the above definition.
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