Limit Theorems in Probability Theory
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Questions and Answers

What do limit theorems in probability theory typically investigate?

  • Properties of a function of a sequence of random variables as the sequence length approaches infinity (correct)
  • Properties of a sequence of random variables as the sequence length remains constant
  • Properties of a single random variable as its value approaches infinity
  • Properties of a function of a sequence of non-random variables as the sequence length approaches infinity

What practical benefit do limit theorems provide?

  • They allow us to compute exact quantities without approximation
  • They provide a way to compute the exact mean and variance of any random variable
  • They allow us to use limits as approximations for quantities that are difficult to compute exactly (correct)
  • They provide a way to compute the exact distribution of any random variable

In the example given, what does the sample mean $\overline{X}$ represent?

  • The average of the random variables $X_1, X_2, \ldots, X_n$ (correct)
  • The variance of the random variables $X_1, X_2, \ldots, X_n$
  • The limit of the random variables $X_1, X_2, \ldots, X_n$ as $n \rightarrow \infty$
  • The expected value of the random variables $X_1, X_2, \ldots, X_n$

If the random variables $X_1, X_2, \ldots, X_n$ are independent and identically distributed (i.i.d.) with mean $\mu$ and variance $\sigma^2$, what is the expected value of the sample mean $\overline{X}$?

<p>$\mu$ (B)</p> Signup and view all the answers

If the random variables $X_1, X_2, \ldots, X_n$ are independent and identically distributed (i.i.d.) with mean $\mu$ and variance $\sigma^2$, what is the variance of the sample mean $\overline{X}$?

<p>$\frac{\sigma^2}{n}$ (A)</p> Signup and view all the answers

What does the fact that the variance of the sample mean $\overline{X}$ decreases as $n$ increases indicate?

<p>$\overline{X}$ is likely to be close to $\mu$ for large values of $n$ (C)</p> Signup and view all the answers

What does it mean for a sequence of real numbers $a_n$ to converge to a real number $a?

<p>For any $\varepsilon &gt; 0$, we can always make $|a_n - a| &lt; \varepsilon$ if $n$ is large enough. (A)</p> Signup and view all the answers

Why can't we say that the sample mean $\bar{X}$ converges to the population mean $\mu$ in the same way that a sequence of real numbers converges to a real number?

<p>Because we can never guarantee that $|\bar{X} - \mu| &lt; \varepsilon$ for some $\varepsilon &gt; 0$ and large enough $n$. (A)</p> Signup and view all the answers

What is the main idea behind the law of large numbers?

<p>The probability that $|\bar{X} - \mu| &gt; \varepsilon$ goes to 0 as $n$ increases, for any $\varepsilon &gt; 0$. (D)</p> Signup and view all the answers

What is the key assumption needed for the proof of the law of large numbers presented in the text?

<p>The random variables $X_i$ must have finite variance $\sigma^2. (D)</p> Signup and view all the answers

What is the meaning of the notation $\bar{X} \xrightarrow{P} $ as $n \to \infty?

<p>The probability that $|\bar{X} - \mu| &gt; \varepsilon$ goes to 0 as $n$ increases, for any $\varepsilon &gt; 0. (A)</p> Signup and view all the answers

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