Let $(X_n)_{n \geq 1} $ be a sequence of iid random variables uniformly distributed on the interval [1, 2]. I want to show that it exists a real number $c$ s.t. $ \lim_{n \to \infty} \left(\prod_{i=1}^{n} X_i \right)^{1/n} = c $ almost surely.
To do so, I got the hint that I sould show that the following holds:
For a deterministic sequence $(x_n)_{n\geq 1}$ it holds that $$\lim_{n \to \infty} \left( \prod_{i=1}^{n} x_i \right)^{1/n} = c \iff \lim_{n \to \infty} 1/n \sum_{i=1}^{n} \log(x_i) = \log(c) $$
Questions:
- Why is this useful/helpful to show the hint?
- How can the hint be shown?
- What has to be concluded by the hint in order to answer the "real" question?
Edit: I tried to show this as following:
Let $\log(c) = \frac{\sum \log(x_i)}{n}$. Since the random variables $\log(x_1), ..., \log(x_n)$ are iid, we can apply the SLLN, thus: $\log(c) = \frac{\sum \log(x_i)}{n}$ converges a.s. to $\mathbb E(\log(x_1))$, which equals to: $\frac{1}{2} (\log(1) + \log(2))$.
Is this correct until now? How to conclude?