Expected Value
HTML-код
- Опубликовано: 4 май 2009
- Thanks to all of you who support me on Patreon. You da real mvps! $1 per month helps!! :) / patrickjmt !! In this video, I show the formula of expected value, and compute the expected value of a game.
The final answer represents the net transaction to you!! It means you can expect to be $0.875 richer than before you played the game, on average!
For more free math videos, visit JustMathTutoring.com
to be honest, it has been a long time since i taught stats. i plan on making some vids over the summer (too late i know) about stats though. i need to refresh myself first though.
I have a final in 6 hours and you always save me, thank you so much!
ur hot
good luck!
So you already have your bachelor ?
You're my favorite math tutor on RUclips. I've passed my math classes thanks to you. I just wish you had more stats videos!
Thank you!!
i have been doing some search on this topic for a while, and this is probably the best explanation i have seen. good job
I am in tutoring for the first time in my life because my college xfer from JC to UC depends on this stats class and my gpa (which is fine, except for math). I am really determined to do well in this class, and this video is great. I learned today in psych that if you go home and review the material the same day that you learned it in class, it will help you to retain it- so I can sit here and eat dinner while learning and solidifying my understanding. You're passing me through college!
I seriously wish you were my STAT prof. Your videos teach more than my prof ever could.
I was pretty sure I understood the gist of this while working on a problem but was double checking my work. Stumbled here and you clarified it. Thanks!
@yuyupb sure, but i would just draw pictures and not actually answer anything
I wish my stats teacher could explain stuff simple like you. Great vid, helped me out a lot
Thank you. This helped me understand expected value the day before my final.
Im with u....
thank you so much for your help on this! This makes so much more sense to me now!
@BlikeNave there have also been numerous studies done that show if you study/read something right before you go to sleep, it much more readily gets processed into your memory.
i used to always look at important stuff for about 10-15 minutes before sleep... you will find you are thinking about it while you lay there, which can be good and bad!
Ur a great teacher everytime I don't get something I go to you! Thank you.
@Stirfry0 no, this is not ap calc
Thank you very much!!! I really appreciate this video!! It's helping me out with a different kind of example. Thanks again!
Very simple explanation to a seemingly tough concept! Thanks!!
Excellent. Very clearly explained and simple to understand.
@Agilulfa Actually, to make the piece of information "It only costs $1 to play" relevant, we would have to change all the variables, to make X stand for the amount of money one would win, but again, (-1, 1) would not be valid. Instead, the values would be: X= {-1, 0, 1, 9}, and P(X)= {1/2, 1/8, 1/4, 1/8}, and the expected value of X would be = (-1)(1/2)+(0)(1/8)+(1)(1/4)+(9)(1/8) = 7/8, which is the same answer given, but justified enough, and for how much one would win, not for...
My sisters is in 3+ right now and your video managed to get into her head how to do these problems and I just wanted to say thanks. I had no idea how to do these and you saved my butt. This happened the night before finals for the added stress.
@ThisIsMe812 i was not offended in the slightest. just pointing out that 99% of what you learn in school ends up being useless. people just seem to fixate on math though for some reason (i guess cause they have to think).
Thanks a lot. I've watched your videos for pre-calc and everything. I'm taking AP stats right now and having a lot of troubles.
Nice lecture! Thanks!
One step closer to not failing my Alg2 class. Thank you very much :o
I guess this is the best explanation!! thank you!
thank you very much Mr. Patrick
your lessons are much much better than my teacher's lessons !
the way you explain the details in a very simple way makes it easy to understand
thanks again
your student from saudi arabia :)
Thanks Mr.Patrick!
@ThisIsMe812 and besides, how much of what you learn in school do you use in 'daily living' ? having a job usually means having a skill and having it mastered better than others. if math is not gonna be your skill, that is fine, but for some, this is a skill that makes money! me for example... i make my living understanding math! so to me, it is extremely useful : )
this was very good thank you alot i am majoring in economics im in my first year and statistics has me lost without words but u did a great job thank you alot
@Srjuanando thanks : )
Amazing video sir!
THANK YOU!!!!!! This was a great, easy explanation.
Well, I failed stats last year and I am doing everything - even RUclips - do pass this year. Thank goodness I clicked on your videos. Our professor should watch your videos to see how it should be explained.
Patrick you're just so funny and amazing all at once. So grateful 4 ur vids :D
If a had a teacher like him in college , I would be now a Nobel price winner in maths.
Bravo - this is honnestly the way for teaching childs in a pleasant way. Bravo - Patricos Koronos
Thanks! Really helpful!
Great video. Thanks a lot.
Gorgeous video sir
i swear if i hadnt seen this video i would of failed thanks i like how you dont make it sound confusing this vid should have a million views
@The100mis you miss the point: you win $.875 on average, so after 100 games, you would be up about $87.50.
and of course, it IS possible to be down money (try going to a casino)
I started EV chapter today and i was lost..it helps me a lot..thanks.
I'm looking for creative ways to express the expectancy-value theory of motivation for a graduate class in adult learning. I just might use this! Math is not at all what I initially had in mind, but I love this and think I can spin it to work for my project. Thanks!
thanks!
Thank you so much!:) I'm taking liberal arts and a lot of it is expected value.This helped me!!
this is really helpful, thank you!
very interesting . well explained
04:24
The sum of all probabilities must be one. ( Is it according to kolmogorov's system of axioms?) The way you have written it, the sum is 0.
care to show your thought process ?
@@vegancog4628what is unclear?
Great example, you made this so much easier to understand. Thanks.
yo you here from a homeschooling website, particularly discoveryk12 aswell?
Thank you for giving an example verse all other math teachers who just give equations and your expected to just understand it.
God bless u. The explaination is as simple as it should be
so if I played 100 times spending $100, would ! win $87.50 back but lose $13.50, or would i win back the $100 plus $87.50?
If you started with $100 you'd come out with $187.50.
@@johnbrewer7221 awesome.!
Never really paid attention in stat class..... exam in about a week....No problem I got patrickJMT to help me :D
Thanks this is alot of help!!
THANK YOU! The videos my instructor posted were so confusing and this method puts it into a perspective that make sense to me.
glad i could help :)
Thanks for the video.
Helped lots thanks
best explanation, thank you!
Patrick, can you explain the Proof for the E(X)?
Thanks for making a statistics video that isnt the most boring thing on the planet
THis helps a LOT! THanks:)
lucky that I didnt listen to the professor
Thank you very much, you explained it perfectly
Glad it was helpful!
Thank you so much!! :)
@laucherhan I think the 1 dollar you spend in each game is already factored in calculating the E(X)
Thanks for the help - these vids really do help. Question for you, how much WOULD you pay to play this game...assuming a risk:reward ratio of 1:3?
Wow thank you so much!
One million subs, congrats!
thank you! ;)
@patrickJMT Taking into account my other commentary (9 months later than these ones), I think there's confusion over what X stands for. If it standed for what one would WIN, not HAVE, and the expected value of X = $0.875, then, after 100 games, one would win $87.50, and one would have $187.50. That could have made it clearer for The100mis, but I guess she's not interested anymore...
great job btw it really helped
very good.
thank you
Wow, you actually make statistics fun! My teacher is hopeless
@ThisIsMe812 i bet almost every decision you make in life is really some variation of expected value. for example i mean, why not drop out of school? because the probability of getting a decent job goes up with an education. does one have to go to school to get a good job? of course not...
Can u explain me how does this even work
I wish you were my professor !!!
you sir. Have earn't yourself a new subscriber.
helped alot thanks
And so the day before the midterm, not only did I learn that there was a God, but that he posted youtube tutorials on statistics.
This is very useful for my Rust gambling base.
Would it not make more sense to subtract one from each of the positive outcomes? While you will definatly lose $1, if you land on $2, you gain $2, so overall you win $1. So there would be a 50% chance you lose $1 overall, 12.5% chance you break even, 25% you win $1 etc. Also, I was taught the probilities should add up to 1.
So I think you so do a follow up where you make the bell curve and calculate the Standard deviation. Use a problem simialar to this. or if you want this on since you already have the mean. I wonder would it follow the empirical rule?
Dear Patrick- Thanks for the video as always helpful. However, I believe that E(X) is independent of the number of times the game is played so whether you play once or 100 or 1000 times the E(X) will remain 0.875.
this is not only teach us how to calculate the expexted value for exams its also explain the logic behind the lottery games in general 👍
sooo helpful!
First let me say I wish you were my math teacher! Second thanks for all your videos they are getting me through my advanced math in university! Can you help me with this:
your friend bets you $20 that he can pull 2 spades in a row from a deck of 52 cards (which contains 13 spades). What is your expected value from this bet?
a. 17.65
b. 17.76
c 18.24
d 18.57
The expected value from this bet it depends from the number of spades your friend will pull out.
if he will pull 0 spades --> you will win 20$
if he will pull 1 spade --> you will win 20$
if he will pull 2 spades--> you will LOOSE 20$
GIVEN THAT THERE ARE 2 TRIALS
The prabability of pulling out 0 spades is: (13C0 * 39C2) / 52C2 = 741/1326
The probability of pulling out 1 spade is: (13C1 *39C1) / 52C2 = 507/1326
The prabability of pulling out 2 spades is: (13C2 * 39C0) / 52C2 = 78/1326
The expected value of this bet will be:
(20$ * 741/1326) + (20$ * 507/1326) + (-20$ * 78/1326) = 17.65 (rounded to the second decimal)
hope i helped!
@@katsilianouzafeiria6037 brilliant!
not everyone will see this.... it is taught in just about any statistics class, and sometimes in a probability/discrete math class.
@patrickJMT so you were saying, if I play 100 times, after invested $100, I will have $87.50 in my pocket?
I got it right!!!! :) thanks for sharing!!!
At first it seems like getting $0.875 for spending a $1 is a bad choice. Is the right way to interpret this Expected Value problem as:
"I'm spending $1 to receive an average of $1.875 per spin, thus netting $0.875?"
my teacher can`t teach.. I just realised why it makes sense. this video is so helpful...thx
Just Awesome!!!
goooooooooooooood luck! : )
How do you do this if you aim to win the 10 dollars in 4 tries? Then what will your expected outcome be? I can do this basic stuff, but I just recently got hit with an intense version about shooting darts and I can't figure it out for the life of me.
Beautifully explained. I will use this money example. It's effective. XD
@yoshiyambao Taking into account my other commentary, I think there's confusion over what X stands for. If it standed for what one would WIN, not HAVE, and the expected value of X = $0.875, then, after 100 games, one would win $87.50, and one would have $187.50. That could have made it clearer for The100mis...
Could you possibly help me with a stats question???
Mary has a free token to play a game. The probability that Mary will win the game is 0.05, so the probability that she will not win is 0.95. If Mary wins, she will be given $100, while if she loses, she must pay $5. Let X = the amount of money Mary wins (or loses).
What is the expected value??
THANK YOU!
You're welcome!
If you win a dollar, you just get your dollar back, so that's (0*.125) or one-eighth of the spinner. Zero times anything is zero so you can leave that off if you want.The chance that you would lose your dollar is fifty percent, or expressed as a probability is .50 since the zero takes up half the spinner (-1*.50). The 10 dollar space pays off only 9 dollars since you don't get your dollar back, and that is one-eighth of the spinner, or .125 as a probability (9 *.125) The 2 dollar pays only 1 dollar since you don't get your original dollar back or (1*.25)
(0 *.125)+(-1*.50)+(9*.125)+(1*.25)=.875
cool. thanks
I really wish you had some expected value vids for advanced graduate level math like stochastic processes...those are such a pain :/
@patrickJMT i believe what ur saying is.. gambling is a loosing game..unless u got lucky..but this game...a "low risk game" ?
thx man
u r the man..