Main content
Course: AP??/College Statistics?>?Unit 8
Lesson 4: Combining random variables- Mean of sum and difference of random variables
- Variance of sum and difference of random variables
- Intuition for why independence matters for variance of sum
- Deriving the variance of the difference of random variables
- Combining random variables
- Combining random variables
- Example: Analyzing distribution of sum of two normally distributed random variables
- Example: Analyzing the difference in distributions
- Combining normal random variables
- Combining normal random variables
? 2024 Khan AcademyTerms of usePrivacy PolicyCookie Notice
Combining random variables
Problem
A vending machine that serves coffee pours a varying amount of liquid into a cup with varying mass. Assume that the masses of the liquid and the cup are independent.
Here are summary statistics for the masses of the liquid and the cups:
Mean | Standard deviation | |
---|---|---|
Liquid | ||
Cup |
Let the total mass of a randomly selected cup filled with liquid from this machine.
What is the standard deviation of ?