How to Calculate Conditional Probability

[@saokoc]

11 years old and is still the clearest video i've come across so far. The visuals helped so much. I appreciate you!!

[@shockvoz1234]

Please continue to post these very clear and concise explanations. These videos are by far some of the most clearest explanations of statistics. Probability of finding a video as this: one in a million.

[@statisticsfun]

Thank you so much for your positive feedback! Much appreciated. Make sure you like MyBookSucks on Facebook (see link in video description). This will help other students find the educational video. Good luck in your classes, too!

[@statisticsfun]

Thank you for the feedback! Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@statisticsfun]

The pace is always hard for me because the KZbin audience is so diverse. My target audience are those students that are struggling with statistics and I have learned that for a struggling student the pace can never be too slow.

[@statisticsfun]

Wonderful to hear the videos are helpful for you and I do appreciate the feedback. Make sure you like MyBookSucks on FaceBook (see video description for link). This will help other students find the educational videos.

[@statisticsfun]

Appreciate the great feedback. Make sure you tell your friends and classmates about MyBookSucks and like us on facebook to (see the link in the description of the video). Thanks again!

[@huseynhajiyevakif]

youtube - helping bachelors since 2007

[@statisticsfun]

I think you are referring to when I change the problem starting at about 5:34 in the video. In the second half of the video, I change the problem from P(B) being an odd number to P(B) being equal to 1. Make sense? If not let me know and try to expand on your question a bit.

[@statisticsfun]

You are very welcome. I appreciate questions because it helps me understand what students are struggling with and then I can create right videos.

[@statisticsfun]

You are very welcome and I do appreciate the feedback. Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@statisticsfun]

The pace and length for me is always a struggle because the KZbin audience is so diverse. Thanks for you input.

[@statisticsfun]

Thank you for you feedback. Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@statisticsfun]

Great suggestion and it is my plan to have a series of videos on Bayes Theorem. I hope to have one done within the next week or so.

[@statisticsfun]

You are very welcome. Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@kellyjameson749]

Thank you! I'm taking stats for the first time this year as a senior in high school and most of it comes pretty easy but this is something I was never able to wrap my mind around! This was very helpful for me and I feel so relieved!

[@statisticsfun]

Good question. If you look at the video starting at about 4:30 you will see that I use P(A) and P(A) and the intersection is P(A∩ B) not P(B). Is this what you mean? If not let me know the time in the video that you are talking about.

[@jakobmetzradt7703]

Thank you so much, My teacher taught us this today, and he lost me in the beginning, you made it easier to understand what P(B) and P(A) is. I watched the video twice and I am starting to understand it more and more. Thank you.

[@statisticsfun]

Many Thanks! Make sure you help me spread the word about the free videos. One thing that helps is if you like MyBookSucks on Facebook (see link in the video description).

[@statisticsfun]

You are welcome! Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@westside907]

spent whole night tryna learn conditional probability this video taught it the best

[@statisticsfun]

Great to hear! Make sure you like MyBookSucks on FaceBook (see link in video description). This will help me spread the word about the educational videos.

[@statisticsfun]

Well thank you very much and I appreciate the feedback. Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@statisticsfun]

Thanks and it is my plan to build examples to help people do better on the GMAT / SAT / ACT, etc.. Good luck on your GMAT too.

[@gloriouscubeshine]

Great, I've a Stats exam in a few weeks and you're making my life a lot easier with these videos!

[@statisticsfun]

Yes, you can use a decision tree to help understand conditional probabilities.

[@statisticsfun]

That is great to hear. I was going to name my company/website/FB page -- MyProfessorSucks but went with MyBookSucks instead :). Make sure you like MyBookSucks on FaceBook (see link in video description). This will help other students with horrible professors find the videos. Thanks!

[@statisticsfun]

Thank you and good luck in your classes. Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@mattdesjardins5981]

You’ve been the first person to get me to understand this. Thank you!!!

[@regielb1]

Great example! The first time I have seen a complicated subject explained in very understandable terms.

[@statisticsfun]

Well, thank you! Make sure you like MyBookSucks on FaceBook (see link in video description). This will help others find the educational videos.

[@statisticsfun]

Great to hear and good luck on your test too! You can do it.

[@breakdancerQ]

This was an absolutely incredible video. Far and very far better than a stats course I am doing.

[@padurani]

Thanks for clearing my basics. I am studying after 16 years and preparing for CFA.

[@joshuafancher3111]

Thank You! This is the best explanation of conditional probability I have come across. The Venn diagram and the verbiage "they interset 2 out of 6 times" really drove home the meaning of P(A∩B)

[@stoicfloor]

Even better than my teacher. Precise, to the point, easy to understanding. How I wish you were my Math teacher:(

[@statisticsfun]

That is great! Make sure you like MyBookSucks on FaceBook (see link in video description). This will help me spread the word about the educational videos.

[@statisticsfun]

You are welcome and good luck on your CFA!

[@Aarozinho]

This was the clearest explanation of this concept I've seen anywhere. Thank you.

[@statisticsfun]

Thank you so much. I try to use 21st Century Tools perhaps that is the difference. Make sure you like MyBookSucks on FaceBook (see link in video description). This will help me spread the word about the educational videos.

[@statisticsfun]

Many thanks for your feedback, much appreciated.

[@anitasmith7764]

So easy to understand. I didn't feel it was to slow at all, bc I need time to process what you say before you start on something else. great job!

[@irishamelin4887]

I was getting so frustrated because I couldn't figure this out but your video was a LIFE SAVER. Thank you so much!

[@stephaniemcmullin656]

THANK YOU! After numerous searches I finally came across your account! This is the one that made it click!

[@BasicYutuber]

Why does everyone seem to skip the final fraction simplification? I can't figure out how you add, subtract, multiply, etc. fractions. I'd like to know how you got 2/3 from (1/3) / (1/2).

[@gavinhaugen9831]

When you divide by a fraction the rule of thumb is to flip the denominator and then multiply the fractions ex) (1/3) / (1/2) = (1/3) * (2/1) = 2/3

[@jerfersonmatos28]

If you don't know the basics of fractions enough then why are you studying probability in the first place?

[@statisticsfun]

Let me know when in the video you are questioning. This will help me answer your question.

[@shockvoz1234]

Will do. I'm studying to become a math teacher and find these videos to be of tremendous help ;)

[@blurredmeh1313]

i got it finally.......a great help for my CAT preps...thnx prof...

[@basalduat]

Indeed! This is a visual learner's paradise. Very well done! I'm so glad I found this site!

[@statisticsfun]

I don't have anything on Bayes yet, but I plan on creating something in the next few weeks.

[@kb101bk]

you explained this really well and i appreciate that you went slowly, thanks so much!

[@coolcatj7]

And thx for actually taking the time to at least go through some of these, and thx for the econ videos they really were super valuable for International Econ class and understanding the trade models.

[@laurendutton4881]

Thank you so much for making conditional probability much clearer. I still have one question though. Could you show the same example, but with the P(A) and the P(B) being for much larger pools of data, where it would be impossible to draw the overlapping segment. I'm still having trouble visualizing that. Thank you

[@notoriouswhitemoth]

If I'm understanding your question correctly, it should be the exact same calculations, the only difference is that you wouldn't be able to illustrate your whole sample space in a Venn diagram. For example if you want to figure out how many face cards out of a hundred poker decks are of a particular suit, A would be the total number of face cards (1,600), B would be the number of cards of that suit (5,200). You're not going to be able to visualize that, but it's the same equation: 400 (number of face cards in each suit) /1600 (total number of face cards) =1/4

[@notoriouswhitemoth]

notoriouswhitemoth correction, 1,300 cards of any given suit

[@dzsiegel]

Using the visualization of the dice was very helpful. That alone allowed it to click for me. Thanks!

[@coolcatj7]

If both events have a 3/6 chance of occurring you can square the events to get 9/36 which is the joint probability right? Now, b/c this is a conditional you divide the joint prob by the conditional event which is 3/6. So, 9/36-the joint prob-divided by the conditional (3/6) is 54/108 which in decimal form is .5 which I got for the answer using the formula. Without the formula 2/3 makes sense for the answer. Hopefully that wasn't too confusing.

[@statisticsfun]

While I can't be your teacher, I can post videos for you. And I do call myself the "professor of the universe" :)

[@nima90]

Re-Brushing this for GMAT, very well done. Should give some thought on using actual example from standardized tests.

[@elala02]

I have final exam in the morning, needed refresher, and love the slow pace !

[@statisticsfun]

I believe your conclusion for joint probability is incorrect. It should be 2/6 not 3/6. You could roll a one or a three, these are odd and less than four. These are the 2 possibilities. Not sure where you are getting the 3 or for the 3/6.

[@karaganiamwamlole6412]

I just became the 1000th person to like this video because you, sir, deserve it. Thanks!

[@TheMacksDaddy]

Hi love your videos, but I need help. Do you have a video for a problem like: A pizza place - 70% of pizzas sold have sausage, 50% have extra cheese, 25% are neither. What is the probability that a randomly selected pizza has sausage and extra cheese? The 25% neither factor is screwing me all up. Thanks!

[@statisticsfun]

Great to hear... maybe you could send a link to your teacher :)

[@sunitamathew4877]

How do you know which is A and which is B? Why couldn't I put "knowing that the value is an odd number" as my B and then having the "rolling a dice and it's value is less than 4"? I'm concerned that when I'm given another example, I wouldn't know how to put the A and B accordingly in it's place. Thanks in advance for your help.

[@statisticsfun]

You can only square the probability of two events occurring simultaneously if they are independent. These probabilities are not independent. This is called the "multiplication rule for independent events."

[@indexoverflow]

Great videos, they've helped me a lot. I'm very impressed by the illustrations and was thus wondering if you could share what program(s) you've used to make these videos?

[@yesil1026]

What if A event is impossible? I've encountered such a problem like "Knowing that dice is rolled greater than 6" or something like that. Then what is P(B|A) ? is it 0 or undefined because of the denominator in P(B|A) = P(AnB)/P(A) equality?

[@cindyash9018]

Thank-you so much! I've been in the hospital for a while and I have a lot of school work to do. Most of it is easy but conditionals are super difficult. I've never seen anyone who made math this understandable!

[@djruv]

Is there a relationship between decision trees and conditional probabilities?

[@heyooyeh9059]

How do you claculate P(AnB) tho?? Like i get it with a venn diagram but what if i have to calculate it without the diagram? Is it like P(A) x P(B) or something??

[@ryanpohle3725]

i would have liked if you showed mathematically how to find (PandB) instead of illustrating it through a representation. How am i supposed to use a venn diagram when i have huge numbers covering probabilities like peoples income and their education level and the correlation? Is it fair to say (PandB)=P(a)*P(B)... No. so how the heck do i find P(AandB) when i dont have an easy little representation to find it.

[@coolcatj7]

I probably misunderstood you. I get that only {1,3} are odd and less than four. But how did you get 2/3 for the answer using the formula? If P(B)=rolling a value < 4, which its probability is 3/6 or 1/2. P( A)= knowing the roll is odd, which its probability is 3/6 or 1/2. Formula P(B given A)=P(A*B)/P(A). 1st multiply the two events for joint prob, (3/6)^2. I got 9/36 or 1/4. Then divide that by the new sample space which is A or 3/6 for .5 or 1/2 as the answer.

[@coolcatj7]

I'm most likely wrong. But will try again. The Blue circle:prob of rolling less than a four, not less than or equal to is {1,2,3} or a 3/6 probability, for rolling a value < 4. The green circle: knowing the roll is odd is {1.3.5}, therefore its probability is 3/6. So events A & B should have a 3/6 probability, respectively, right? Now, to find the joint prob you multiply the probability of the two events ( the green and blue circles) which both events have a 3/6 chance, right?

[@rostammalik2071]

Your teaching process makes me easy to understand.Thank you sir.

[@Josh-jo1zn]

what do you do if the denominator has 2 different out comes after simplifying and you're trying to find an over all probability of something happening

[@atanugg9372]

one of best intuitive animated video make probability learning more fun..thak you sir.

[@Photon98]

Can you come up with Interpolations & Extrapolations? Linear, Cubic, Splines?

[@asrarmostofa818]

do you have multipal regression lecture

[@SequinBrain]

Not picking on you at all, since I see these dice problems in my text (Horgan), but how is it possible to know that a die is going to be odd prior to rolling it? I need this power!

[@mz_sophier4253]

how do u work a problem that doesnt give the sample space eg. A/B = 1/5 , B/A = 1/3 what is a& B ? what is A?

[@heyitsuhmm]

Hello sir!I really find your videos very easy to understand (coming from a stat-challenged person :) ) But, I think I missed something on this one, why is B in P(B) becomes the intersection of A and B?Why not A as the intersection of A and B?I'm confused.Sorry, and thank you!:)

[@sea20era]

Super helpful and working step by step is super helpful. Thank you so much for this video!

[@statisticsfun]

You are very welcome.

[@sydneyslabosz7847]

really helps seeing it drawn out and explained step by step like this, really helps thank you!

[@DL-nd3mj]

Do you have any other channels for C1 C2 etc?

[@statisticsfun]

Do make sure you "like" MyBookSucks Fan page on Facebook. I have some fun items (like my freshman student ID) and other college humor.

[@64z]

This was amazing!!! I was trying to figure out (the sum is at least 10, given that the sum is at least 9). I figured it out after watching this video!! Thx!

[@myeshacbj]

Thanks this helped! Your wording of the formula is what made the difference for me! :-)

[@TheJebacina]

Dear Statisticsfun What is difference between this and bayes theorem?

[@sarahalloush3170]

Hi, Thank You SOO MUCH for your work!! Its very clear, especially with the animation. Brilliant idea. Can you just explain to me why the P(A intersection B) has a denominator of 6, in the second case? Thank You

[@christian_aviles3]

How did you get a simplified answer of 2/3?

[@elainesingh4343]

Hi! Thank you. This was so helpful considering the fact that I have been finding stats so difficult.

[@statisticsfun]

The intention of the video is to introduce the idea of conditional probability. It does not matter if you are using large samples or populations the basic principles are the same. What proportion of the people have a college education and an income over 100,000 as an example. I imagine you are trying to solve some sort of homework or research problem?

[@agila.p9807]

How is A intersection B 1/3? can you please explain the logic?

[@SalK-3S3K]

What is the logic of (A intersection B) in the equation?

[@cherieminn2673]

my best teacher ever💯👍🏻 my QUANS teacher sucks!

[@maheennadeem7760]

You are the best. Man, love your videos, keep it up. You deserve a like and a subscriber. Thanks.

[@warnerwildernessphotography]

Better than my math teacher... Thank you!

[@gloriouscubeshine]

That was great and couldn't have come at a better time! Thanks! Could you do something like this for Bayes Theorem please?

[@SirFD_]

What is the difference between Non-Mutually Exclusive events and Conditional Probability events?

[@vinna01]

Assume a variable X with three possible values: a, b, and c. If p(a) = 0,4, and p(b) = 0,25, what is the entropy of of X, i.e., what is H(X)? can you show me the calculation step by step?