# What is random variable of rolling two dice?

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A random variable is a numerical measure of the outcome of a probability experiment whose value is determined by chance. … Rather than looking at the dice individually, we can instead look at the sum of the dice, which would be a random variable. In this case, if we let X = the sum of the two dice, x = 2, 3, 4, …, 12.

## Is a dice roll a random variable?

Usually, random variables are denoted by a letter like X or Y. For rolling a pair of dice, you could let X be the sum of the numbers on the top. Then you would write the probability that the sum is 6 as P(X=6). … The expected value of the random variable is (in some sense) its average value.

## Is rolling two dice a continuous random variable?

Recall that a discrete random variable is one that can only take on one of a number of discrete values, and nothing in between. For example, a die (singular of “dice”) can come up 1, 2, 3, 4, 5 or 6, but not 1.5 or 2.3. That’s a discrete random variable. …

## How do you find the random variable?

The formula is: μx = x1*p1 + x2*p2 + hellip; + x2*p2 = Σ xipi. In other words, multiply each given value by the probability of getting that value, then add everything up. For continuous random variables, there isn’t a simple formula to find the mean.

## What is the expected value of rolling 2 dice?

For example, if a fair 6-sided die is rolled, the expected value of the number rolled is 3.5. The expectation of the sum of two (independent) dice is the sum of expectations of each die, which is 3.5 + 3.5 = 7. Similarly, for N dice throws, the expectation of the sum should be N * 3.5.

## Why is rolling a dice random?

A die roll is only considered random if the external factors are not controlled. Practiced dice cheats can roll numbers they want to roll. So talk about nerves and blood vessels and quantum effects are just wrong. These cheats control the meaningful factors such that they influence the outcome of the roll, predictably.

## When can you add the variances of two random variables?

Variances are added for both the sum and difference of two independent random variables because the variation in each variable contributes to the variation in each case. If the variables are not independent, then variability in one variable is related to variability in the other. 