6.2.2 - Combining Random Variables

Front

What is the mean of two independent random variables?

Back

The mean of the sum of two independent random variables is the sum of their means.

Front

What is the standard deviation of the sum of two independent random variables?

Back

The standard deviation of the sum of two independent random variables is found by adding their variances and then taking the square root.

Front

If the mean weight of a bag is 36 pounds and the standard deviation is 3.5 pounds, what is the mean weight of two bags?

Back

72 pounds.

Front

What is the formula for the variance of the sum of two independent random variables?

Back

Variance = Variance(X) + Variance(Y).

Front

If the mean hourly salary for a high school graduate is $13.50 and for an Associate's degree is $19.75, what is the expected difference in their salaries?

Back

$-6.25.

Front

What is the standard deviation of the difference between two independent random variables?

Back

The standard deviation of the difference is found by adding their variances and taking the square root.

Front

What is the mean weight of a dog (34 pounds) and a cat (12 pounds)?

Back

46 pounds.

Front

If the standard deviation of a dog is 6.7 pounds and a cat is 3.1 pounds, what is the standard deviation of their total weight?

Back

7.382 pounds.

Front

What does it mean if two random variables are independent?

Back

It means the occurrence of one does not affect the occurrence of the other.

Front

How do you calculate the variance of the difference of two independent random variables?

Back

Add the variances of the two variables.