Variance of a random discrete sequence

1. How do you find the variance of a discrete random variable?
2. How do you find the variance of a random sample?
3. What is the variance of a random variable?
4. How do you find the variance of X Y?

How do you find the variance of a discrete random variable?

For a discrete random variable the variance is calculated by summing the product of the square of the difference between the value of the random variable and the expected value, and the associated probability of the value of the random variable, taken over all of the values of the random variable.

How do you find the variance of a random sample?

Given a sample of data of size n , the sample variance is calculated using s2=1n−1n∑i=1(xi−¯x)2.

What is the variance of a random variable?

In words, the variance of a random variable is the average of the squared deviations of the random variable from its mean (expected value). Notice that the variance of a random variable will result in a number with units squared, but the standard deviation will have the same units as the random variable.

How do you find the variance of X Y?

If X and Y are uncorrelated, then Var(X+Y)=Var(X)+Var(Y).