Sum of discrete uniform random variables

In summary, the problem asks for the distribution of a sum of random numbers between 0 and 1 with decimal digits that are independent and uniformly distributed. This can be visualized as a random number between 0 and 1 with iid digits, and the distribution is likely to be uniform.
  • #1
avidaware
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Homework Statement


Let ##X_k## be iid uniform discrete on ##\{0,...,9\}##. Find the distribution of ##\sum\limits_{k=1}^{\infty} \frac{X_k}{10^k}##

Homework Equations


The Attempt at a Solution


I've tried a lot of things, I've tried decomposing ##X_k## into 10 bernoulli trials, I've tried using some form of central limit theorem. I've tried calculating the characteristic functions, then taking the limit and I get something really ugly. Any hints? I feel like there is some limit theorem I don't know.
 
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  • #2
avidaware said:

Homework Statement


Let ##X_k## be iid uniform discrete on ##\{0,...,9\}##. Find the distribution of ##\sum\limits_{k=1}^{\infty} \frac{X_k}{10^k}##


Homework Equations





The Attempt at a Solution


I've tried a lot of things, I've tried decomposing ##X_k## into 10 bernoulli trials, I've tried using some form of central limit theorem. I've tried calculating the characteristic functions, then taking the limit and I get something really ugly. Any hints? I feel like there is some limit theorem I don't know.

If you observe ##Y = \sum_{k=1}^{\infty} X_k / 10^k## you will see a random number between 0 and 1 and whose decimal digits are iid uniformly distributed in 0--9. How do you think such a number will be distributed?
 
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What is a discrete uniform random variable?

A discrete uniform random variable is a type of probability distribution where all possible outcomes are equally likely. This means that each value within a range has the same chance of occurring. It is typically represented by a rectangle in a graph, with the height of the rectangle representing the probability of each outcome.

What is the sum of discrete uniform random variables?

The sum of discrete uniform random variables is the total value obtained by adding together two or more discrete uniform random variables. This can be thought of as the combined outcome of multiple independent events where each event follows a discrete uniform distribution.

How do you calculate the sum of discrete uniform random variables?

The sum of discrete uniform random variables can be calculated by simply adding together the individual values of each random variable. For example, if you have two dice, each with a discrete uniform distribution from 1 to 6, the sum of the two dice would range from 2 to 12, with each outcome having an equal probability of occurring.

What is the expected value of the sum of discrete uniform random variables?

The expected value of the sum of discrete uniform random variables is the average value that can be expected to occur over a large number of trials. For discrete uniform random variables, the expected value is equal to the midpoint of the range of possible outcomes. In the case of two dice, the expected value of the sum would be 7, as it is the midpoint between 2 and 12.

What is the variance of the sum of discrete uniform random variables?

The variance of the sum of discrete uniform random variables measures the spread of the data around the expected value. For discrete uniform random variables, the variance is equal to (n^2 - 1)/12, where n is the number of variables being added together. This means that the variance of two dice would be (6^2 - 1)/12 = 35/12.

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