Probability (part 7)

[BethLeonard]

@langengro -- To clarify even further, what he said was correct, what he wrote down was wrong.

He did write:

P(5/5 | N) * P(N) = P(5/5 | N)

He should have written:

P(5/5 | N) * P(N) = P(5/5 ∩ N)

[ritesh024]

@langengro it means the same thing.

[siri4]

very well explained. first it confused me that I read "25" instead of "2s" sometimes :/

[eurojoe9]

what if you can't draw out all of the possible outcomes, for example if u rolled a dice 100 times. is there a formula to determine the # of outcomes?

[overdrivek]

awesome... great way to arrive at bayes theorem and to explain the relation to conditional probability.. really useful!

[InsanePorcupine]

Never mind people I think I have figured it out on my own. Or at least cleared up some misconceptions I had about things. I now understand that my odds of say getting a tails in six flips is 98.4% however my odds of getting said tails goes down with each failure contrary to what you might think. 98.4, 96.8, 93.75, 87.5, 75 ,and then finally 50% for the last flip. Funny that before you flip the first time you have increased odds of getting tails but your odds dwindle with each failure.

[InsanePorcupine]

one more thing if anybody reads this thats been messing with my head and the reason I started watching these vids is if you flip a coin 5 times and get heads every time your odds of getting a heads on flip 6 is still 1/2 yes but is it? I have trouble grasping that 6 heads in a row is 1/64 yet your chances of getting a heads is 1/2 when if you got one it had a 1/64 chance of happening. Your odds of getting a tails does not increase at all? shouldnt the odds of getting tails go up.

[InsanePorcupine]

can someone explain this to me if your odds of getting 5 heads is 1/32 on a normal coin then how come your odds of getting 5 heads when you have a bag of ten coins with one false one go down for a normal coin. Its just confusing I understand you have a pick of 9/10 coins but it just seems counter intuitive that your odds would decrease to about 1/35 but I guess the extra probability in the 1/10 makes up the difference?

[drakezen]

Botany bay? Botany Bay?!! But seriously, great videos! :)

[bookluvr613]

im taking the algebra regent on the 16th, and i didnt learn probibility yet, so im using these videos. but is all of this on the regent?

[MBlu3]

this looked like the starcraft ui from the thumbnail :))

[Tural192]

thanx manwas helpful

[AKAciti]

These classes are very interesting

[askshbni]

very nice thnk u

[alakija]

hi khan, just a point on 4.38 you draw GIVEN but it's AND

[Fyrius]

A visual approach to Bayes' Theorem? I love it! :D

This makes calculating conditional probabilities so much easier for us numerophobes. :)

[V2PRC]

This playlist is not up to the standard of the other playlist on Linear Algebra, Sal. (Understandable, though. Judging from the software you are using, this playlist was done earlier.) There is no proper introduction to sample space and events and axioms of probability etc, and "conditional probability" just jumped out of blue.

I think you need to get things more systematic and a bit deeper into the subject.

[timjamz]

Seriously?.... the Math of Khan??... :-O

[Luca220392]

finals 2morrow !!

[rezaeijavan]

khan , it was too hard !! too complicated , u spoke so messy , i didn't understand :(

[markgarau]

@rezaeijavan Fuck u dumbass ....

[rezaeijavan]

@markgarau what is wrong with you?????

[HairLikeCottonCandy]

KHAAAAAAAAAAAAAAAAAN!!!!

[jamesscottemail]

Wonderful...Superb

kudos to you for this nice work

[daraven442]

Thx, good work

[abab676]

Awesome!!! I absolutlely admire your work Sal! Thanks.

[Rook1515]

THANKS!!!

[clarkindee]

Love your videos, Sal. You lost me a litle on this one but thats okay, I've watched all the others up to this one so probably just a litlte tired LOL!. Bless you for your work on this.

[penguinluther]

i got a little lost on this one too, i think after the hour mark the brain gets a little tired...but i agree, great teacher!

[erikapk]

@penguinluther Haha, me too!

[jpcgandre]

p(a|b) is not p(a) times p(b)!!! if they're independent!!! if they're then p(a|b)=p(a) dahhhh

[jmpeax]

You misunderstood. He said that p(a|b) is p(a) if a and b are independent. He was rewriting the whole RHS, p(a|b)*p(b) => p(a)*p(b) if a and b are independent. He was -not- saying that p(a|b) = p(a)*p(b).

[lilmizsudan]

I am confused to the bone.....I have now lost it....seriously I don't understand....at around 02:35 were you talking about And/Or Rule....if anyone understands please shine a light on me....I've got my Sats.....Year 9 Sats...yes I live in the UK...in about 2 to 3 weeks but I still have trouble with probability....so please people...

[wofong]

Watch Probability (Part6). There you can find that P(5H | Normal coin) * P(Normal) = 1/32 * 9/10, and P(5H | 2sided coin) * P(2S)=1*1/10. He's trying to explain that P(5H | Normal)*P(Normal) = P(5H AND Normal) using graph...

[elpresidio]

Let me see if I have this straight. I know it's a while since you watched this video, 5 months. but 9/10 is the probability of a normal coin, 1/32 is the probability that from a set of only normal coin you get 5 heads, and 1/320 is the probability that with 2 sided head biased coins which accounts for 1/10 of entire rectangle mixed in with the normal coins that you get heads from only normal coins, correct?

[Ratfieldtwo]

As a sixth grade math teacher, hearing a real "grown up" math teacher define probability so succinctly is edifying, however, I was swimming intellectually somewhere after video 5

[beserkanton]

you sound like peggy hill. shut up

[Ratfieldtwo]

This is the first time I have responded to a u-tube...you sound like you are mad at me... and who the heck is peggy hill...

I'm thought I was sharing my appreciation to someone who has dedicated so much time to helping all of us to understand math...more importantly, provide equal access to all...so I don't get this comment...maybe it's like probability...Peggy Hill is some confusing group of symbols???????

[khanacademy]

Don't worry about it. Some people use the Internet to vent their negativity indiscriminately Appreciate your comment..

[SomeUsefulVids]

at 5:12 there's an equation stating

P(5/5|N) * P(N) = P(5/5|N)

The way I see it:

The Left side evaluates to 1/320

The Right side evaluates to 1/32

[shazaduh]

I think it's a typo. It should be P(5/5 and N) where "and" is intersection.

[gforceram]

lost me there but im gonna watch it until I understand it.

[MatteNoob]

good video as usual, Sal. :) You are my favorite mathtutor on the internet!