Random variables | Probability and Statistics | Khan Academy

Basic idea and definitions of random variables

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[Barnekkid]

Why didn't they explain it this way in school? No, instead they turned it into some great big effing mystery until three fourths of the class lost interest.

[WateryIce]

Well, we're at a high enough level at this point. I'm sure others can agree by now when I say - looking forward to another great semester with you Sal. In Calculus 1 you were my backup teacher. But, ever since multi dimensional Calculus its like my actual professors are the backup. Truly, I envy your ability to explain topics so clearly.

[danielcohenemail]

as a senior in engineering i come back to khan academy occasionally after years of listening to sals voice it now has become quite nostalgic

[abhirawat]

I have logged in just to say "thank you for the wonderful lecture".

[mayurp]

How I understand randomness is that it's a measure of knowing that an event will occur but being unsure about its outcome. Hence, we use random variables to map out (or quantify) the outcomes of those random events.

[brco]

A lot of people struggle with probability because they skip over this introductory concept, dismissing it as basic and taking it for granted. However, a solid grasp of this concept will pay dividends when one encounters the core concepts of probability theory and statistics. Thanks, Sal!

[DrCycotic]

I am so glad you exist. Thanks for such a nice and clean explanation

[BoZhaoengineering]

Khan academy is like a video Wikipedia in academic.

[jessicafessler]

you're literally the only reason why I'm managing to get through my business degree

[fuzzywuzzyangel]

You're literally my life saver through college.

[kamolaablazova]

Hello, I always listen to your lessons, I like your speech, you explain the lesson, Please send me simpler textbooks on probability theory and mathematical statistics, from Uzbekistan, teacher Kamola

[poornimas]

please upload problems related to it and discrete probability distribution function

[KeyserTheRedBeard]

excellent video Khan Academy. I smashed the thumbs up on your video. Maintain up the solid work.

[Fennecfox]

A random variable is the same an event? My book tends to use capital X as 'random variable' for probability problems and they use capital A, B, C for Events, subsets of a sample space.Furthermore, capital omega is random space for probability and sample space when discussing events.

Sorry if I made poor distinction, but I don't understand why they is a distinction.

Perhaps a random variable is a specific kind of Event where it is a 'real valued function, and similarily for random space being a type of sample space.

[neenaji]

The question is about variables.

We would say that “height” is a variable. In my mind, “height” does not just represent different values, like 2, 45, or 75. It represents values + units: 2 feet, 45 feet, or 75 feet.

However, when we work with variables mathematically, I believe that we think of them as solely representing values / numbers. For example, we will say statements such as:

height = 2
weight = height + 4
weight = 6

It seems confusing to me to have to think about variables in 2 different ways. Could you explain if I’m thinking correctly? How do you recommend thinking about variables so that I can do statistics most effectively?

Please reply.
Thank you

[malteeaser]

Did it make sense to find the expected value of X when it is assigned by the first method, where you arbitrarily choose random numbers to enumerate heads and tails?

[pedrogaleano]

Very clear explanation! Thank you very much

[MindfulSapient]

Hi! Is this the engineering level Probability and statistics course? I need a place to revise all my engineering mathematics courses including differential and integral calculus, multivariable calculus, linear algebra, differential equations, probability and random variables, numerical methods. Kindly let me know if the maths section here on Khan Academy covers these courses.

[-berkeleyroyyuriahkelly]

what my teacher taught us is this
ex. Number of tails in tossing a coin thrice
ans. {0, 1, 2, 3}

[mosels]

I liked this video. it's so helpful