People keep saying that he is "over complicating" the content. However, the best way to study for a test for example is through complete understanding of what you are doing. Sal explains things in such detail in showing you WHERE equations and methods are derived from and WHY we are using them. With this understanding behind you, you are able to manipulate your knowledge for any question that you're hit with in an exam situation. THANK YOU SAL.
He mentions it quite often... maybe he should add to say: ms paint + a tablet (pc) and a pen + a screen capture software. With this 3 things you can make it like that.
Thanks for this explanation! I just missed a quick explanation on why you multiply by k inside the sum operator, but now I see it's because E(X) should return how many scores you make, so you sum every score possible, each skewed by it's own probability. E(X) = (0 scores)P(X=0) + (1 score)P(X=1) + ... + (n scores)P(X=n)
Expectation is the sum of every outcome times it’s probability. K is every outcome in range from 0 to n, and c(n,p)*p^k(1-p)^(n-k) is the probability X=k.
This one took me a while, but I kept through it and it all made sense! Understanding the longer version of the probability formula took me forever but it was right in front of me lol. Just don't let all the variables intimidate you.
after the change of indexes to a , b , it remains to show that the summation (15:00) = 1. this is easy to see by noting that this summation is the binomial expansion of (p + (1-p))^b ; ie 1^b
I have an exam and this has completely flipped and has completely confused me. It started great but I am trying to learn to solve these in a statistical formula and the easiest way to remember these.
I have a doubt 15:02 - he takes the np out of the summation and says the summation is equal to 1 so E(X) = np but at 06:47 also we can take the K out of the summation and say that E(X)= K ??? Why
I think for 6:47, K are random variables, so their value are different and their probabilities are also different. For 15:02, n and p are just coefficients
12:22 im confused here, why does (a+1) - (b+1) = a-b? why does he switch the b+1 to a b-1 and cancel them out (12:28)? surely n-k here would = a-b + 2?
Sounds very familiar to my professor. If we ask him a question he always looks at his notes handout that he distributes for every chapter and points to a formula. The visual aspect of it is much more helpful.
Hi Mr. Khan, I appreciate your effort for spreading knowledge throughout the world. Your videos helped me a lot to fill the gaps of my lack of knowledge. However, I would like to request you, if you kindly use different example other than basket ball, it would be even better to understand for students like me who are from outside USA. As the game is not so popular in our area, the rule of this game is completely unknown to me. Thank you.
The expected outcome of an experiment involving any number of trials n, is directly proportional with the number of trials. If the expected value of 1 trial is 0,4 than the expected value of 10 trials is 4. If you have 40% chance of making the basket and you take 10 shots, then you'd expect to make 4 of those shots. You really can't perform infinty trials, but as you perform more and more trials the expected value is proportional to the number of trials. That's the way i understand it anyways.
Is there a way to calculate probability of expected value? In our example expected value was 4 in 10shots which implies we are likely to score 4 in 10 shots but how likelt is it?
I assumed it was a tablet aswell but I've thought about it and it can't be. Surely if it was the mouse pointer wouldn't move when he's not writing, no?
At 11:30 you wrote in the denominator (n-k!) when that step you before that you had (n-k)! was that a mistake or is (n-k!) = (n-k)! btw thanks for the video.
I was a little confusing, in previous video "expected value", you said that expected value is some thing like the population mean. Due the population maybe infinite, so wecan not summarize all the numbers in population, we then calculate mean using x1*p(x1)+x2*p(x2)...., but here "Expected Value of Binomial Distribution" is np, how about n is infinite??
Hey Guys, help me out here! If you ask me the probability of making one shot, for me I would say p=30%. While saying this, I am actually providing an estimate that I'll be able to make 3 out of 10 shots for sure (means, P(X=3) given n=10 is 100%) But then using same numbers n=10 and p=3 I calculate the binomial probability of making 3 shots out of 10 and it is 26.68%!
hey anyone wanna explain to me how i would put this equation into a calculator i know how to format it but i dont know how to solve. the thing that makes the least sense is the (n choose k)
in your calculator, u will see a key labelled nCr. that's ur combination key. always put the pick no first, press the shift bottom then nCr then press the smaller no last. e.g 5 chose 3 will be 5 nCr 3. press 5 then shift key, then nCr key, lastly key in 3. then the equal sign. and your answer is 10.
People keep saying that he is "over complicating" the content. However, the best way to study for a test for example is through complete understanding of what you are doing. Sal explains things in such detail in showing you WHERE equations and methods are derived from and WHY we are using them. With this understanding behind you, you are able to manipulate your knowledge for any question that you're hit with in an exam situation. THANK YOU SAL.
💯 In fact he explains in and out and “decomplicates”
Who else doing a whole semester of studying on the eve of their statistics final?
bobagopaaa
Good luck.
NexDemise hahaha just saw this...while cramming for my stats exam - hope you passed
who's not?
Lol I’m watching this in the beginning of class before the 2nd lecture
Midterm but same I guess
Oh look at this! My iPod wants to sync.. he hee. I love this guy, he's doing such a great service to the field of education.. and so casually.
"im talking about basketball not basket weaving.." LOL. And here I thought you were talking about probability of weaving a basket after doing shots :P
Prachi Singh oooh nooooo😜
They need 4k remakes of these videos.
Love it especially the last part where you say "E(X) = np for random variables whose probability distribution gives a binomial distribution"
"My iPod wants to sync" Hilarious.
well you need to get a life @drew G.
Oh my god , statistics and math is magic !
wow this video explained it the best even after 12 years of its release,thanks sal
this is so beautiful i could cry
He mentions it quite often... maybe he should add to say:
ms paint +
a tablet (pc) and a pen +
a screen capture software.
With this 3 things you can make it like that.
When final is 1 day ahead and realize that reading 350 pages is impossible.. AND suddenly this guy gives us perfect playlist
Thanks for this explanation!
I just missed a quick explanation on why you multiply by k inside the sum operator, but now I see it's because E(X) should return how many scores you make, so you sum every score possible, each skewed by it's own probability.
E(X) = (0 scores)P(X=0) + (1 score)P(X=1) + ... + (n scores)P(X=n)
Expectation is the sum of every outcome times it’s probability. K is every outcome in range from 0 to n, and c(n,p)*p^k(1-p)^(n-k) is the probability X=k.
My God, he said it… 5:43
This one took me a while, but I kept through it and it all made sense! Understanding the longer version of the probability formula took me forever but it was right in front of me lol. Just don't let all the variables intimidate you.
dude I was like well this video looks old, then I see it's from 2009 and mind = blown lol, I thought khan academy was at most 5 years old.
after the change of indexes to a , b , it remains to show that the summation (15:00) = 1. this is easy to see by noting that this summation is the binomial expansion of (p + (1-p))^b ; ie 1^b
At 13:18, it should be np* Sum (from a=0 to b+1) not Sum (from a=0 to b)
Man you are god🙂🙂🙂🙂
Extraordinary i am your fan .
This is great explanation! thanks
This is an awesome video! Dear video maker, you are a very talented teacher! :)
he is Khan himself, man
11:25 he messed up the factorial (n-k)!
At 12:34 you say...
n-k = a -b...
It seems like it should be...
n-k = b - a. Am I mistaken?
You are correct, well spotted. Another mistake is that a factorial inside a set of brackets when it shouldn't be at 11:25 .
Mind blown,🤯
Understood. Thanks
12:39 if a + 1 = k, b+1 = n then n - k = b+1 - a- 1 = b - a
I enjoyed this, much better presented than my professor.
It was really really great😍😍😭 thank you sooo much.
That was some seriously cool math you just did there! This is so helpful!!! THANK YOU!
Thank you! I got to the derivation. Except I didn't know what to do with the summation!
I have an exam and this has completely flipped and has completely confused me. It started great but I am trying to learn to solve these in a statistical formula and the easiest way to remember these.
Khan you are the best !
6:50 sigma algebra
I have a doubt
15:02 - he takes the np out of the summation and says the summation is equal to 1 so E(X) = np
but at 06:47 also we can take the K out of the summation and say that E(X)= K ??? Why
I think for 6:47, K are random variables, so their value are different and their probabilities are also different. For 15:02, n and p are just coefficients
Elite thank u
Those videos are just great. Thank you Khan
Great. Tough but certainly enjoyable.
Amazing!!!
12:22 im confused here, why does (a+1) - (b+1) = a-b? why does he switch the b+1 to a b-1 and cancel them out (12:28)? surely n-k here would = a-b + 2?
Awesome explanation thank you!
that's really cool!
I'm in probability and random variables right now. This is a common permutation formula in stats. The correct denominator is 'n!(n-k)!'.
Sir,give some problems we can solve
got it!! ....thank you sir.,.
At the end, it made sense. Thank you! That was a challenge.
I really enjoyed your prob and stat series. Would you please do a video on standard deviation for a binomial distribution.
Sounds very familiar to my professor. If we ask him a question he always looks at his notes handout that he distributes for every chapter and points to a formula. The visual aspect of it is much more helpful.
Would help if you had a proof using the moment generating function too.
You gotta love those last steps in a proof when everything just boils down to something very simple
Hi Mr. Khan, I appreciate your effort for spreading knowledge throughout the world. Your videos helped me a lot to fill the gaps of my lack of knowledge. However, I would like to request you, if you kindly use different example other than basket ball, it would be even better to understand for students like me who are from outside USA. As the game is not so popular in our area, the rule of this game is completely unknown to me. Thank you.
The expected outcome of an experiment involving any number of trials n, is directly proportional with the number of trials. If the expected value of 1 trial is 0,4 than the expected value of 10 trials is 4. If you have 40% chance of making the basket and you take 10 shots, then you'd expect to make 4 of those shots. You really can't perform infinty trials, but as you perform more and more trials the expected value is proportional to the number of trials. That's the way i understand it anyways.
Fabulous! You are amazing.
you have very good & useful tutorials! many many thx for posting!
So it Is basically like an average..at least in some cases...
Awesome sir, YOU are Really making concepts clear
Is there a way to calculate probability of expected value? In our example expected value was 4 in 10shots which implies we are likely to score 4 in 10 shots but how likelt is it?
Use formula: 10c4*(.4)^4*(.6)^6
I assumed it was a tablet aswell but I've thought about it and it can't be. Surely if it was the mouse pointer wouldn't move when he's not writing, no?
from this explanation can i say E(X)=K or K=np ?
Excellent Understood it completely!
He corrected at some later time :). Did you see the full video?
a wonderful proof!
Wow, great video
Great job, well done...
6:49 'Some Sigma Algebra I guess you could call it' --- I see what you did there :D
It was very helpful. thank you.
17 minutes to say E(X)= n•p 😂
Jokes aside, good explanation. √
periodt
yes
At 11:30 you wrote in the denominator (n-k!) when that step you before that you had (n-k)! was that a mistake or is (n-k!) = (n-k)! btw thanks for the video.
It was a mistake!!
Replying to a 5 year old comment🤣😂🤣😂
In the first minute of the video, the mouse pointer was the one explaining the lesson.
(n-k!) should be (n-k)! In the denominator
YEAH!
Fantastic!
Thanks! ;)
Best
why did we multiply by k at 6:23
Great video very good explanation...Little confusing but great effort..!!
Thank u very much,,!!
:P
Very nice!
dude patrick what on the khan? i know its you man
its window paint. he says it in previous video. but i suspect that he has one of those pen pads for computer which helps him write properly
Thank you man, you're a fucking genious
Your god!! Wooh!
good! proof.
this isn`t a proof?
+Geekminer ur face is proof of gayness
市釧路
Have you seen my face?
I saw you while i was eating dinner at your house
I was a little confusing, in previous video "expected value", you said that expected value is some thing like the population mean. Due the population maybe infinite, so wecan not summarize all the numbers in population, we then calculate mean using x1*p(x1)+x2*p(x2)...., but here "Expected Value of Binomial Distribution" is np, how about n is infinite??
Never mind Sal. I see you corrected yourself around 14:00
12: 32 - n-k should be b-a and not a-b
Didn't understand the multiplying by K at 6.25
That's formula for Expectation
Holy shieeet thank you Khan! You're a fookin genius, thank youu =)
he mentions it quite often, it's mspaint.exe
G(old)
Neat
Hey Guys, help me out here! If you ask me the probability of making one shot, for me I would say p=30%.
While saying this, I am actually providing an estimate that I'll be able to make 3 out of 10 shots for sure (means, P(X=3) given n=10 is 100%)
But then using same numbers n=10 and p=3 I calculate the binomial probability of making 3 shots out of 10 and it is 26.68%!
as he taken n=b+1 ..then summation should be from a to b+1 not a to b...
this guy kinda sounds like job benjaminm from archer lol
can anyone explain why p^k= p(p^k-1)?
Hi lets say k =2 so p^2 = p(p^2-1) or p^2 = p*p
toddy huang
p^k = p^k+1-1
p^k = p^1 * p^k-1
p^k = p(p^-1)
bc of
a^m+n = a^m * a^n
his handwriting thou...
It's from 2009 tho..
writing with a mouse is hard
hey anyone wanna explain to me how i would put this equation into a calculator i know how to format it but i dont know how to solve. the thing that makes the least sense is the (n choose k)
in your calculator, u will see a key labelled nCr.
that's ur combination key. always put the pick no first, press the shift bottom then nCr then press the smaller no last. e.g
5 chose 3 will be
5 nCr 3.
press 5 then shift key, then nCr key, lastly key in 3. then the equal sign.
and your answer is 10.
please persian translate , thanks khan academy.
This was way over complicated. Just substitute in your variables in to the formula and solve.
Your probability always adds up to 1.
just scroll down enough and you'll be able to see our ancestors talking about Mspaint.exe and other ancient relics
why 1?
I couldn't understand
You miss 100% of the shots you don't take.