Getting exactly two heads (combinatorics) | Probability and Statistics | Khan Academy

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  • Опубліковано 26 гру 2024

КОМЕНТАРІ • 63

  • @tharunishadi3980
    @tharunishadi3980 12 років тому +29

    i don't know how to live without you.... every-time i got stuck in class...i tell my self ..don't worry khan is there... owe you....

  • @ColaGrain
    @ColaGrain 10 років тому +49

    hahaha i love the grammar frustration with the "heads" :)))

  • @9Coronas
    @9Coronas 11 років тому +17

    I love hearing you have little arguments with yourself.
    You're the man, Sal.

  • @wirechair
    @wirechair 10 років тому +34

    Thank you a million for your simplicity, clarity and not skipping over anything! Thank you! Thank you! Thank you!

  • @DilaraRasulova
    @DilaraRasulova 11 років тому +37

    Thank you for such a helpful videos, Sir.
    P.S In 2:50 minutes in the video there should be TTTH for the 4th possibility.(3rd and 4th are written the same)

  • @woo216
    @woo216 13 років тому +1

    love it when i see 'uploaded by khan academy' on my youtube front page. Good too know khan is still enthusiastic and alive.

  • @mdctoplist4441
    @mdctoplist4441 8 років тому +8

    did you write that with mouse? my god youre good (y)

  • @mintoo2cool
    @mintoo2cool 12 років тому +2

    Dear Sal,
    Please cover advanced stuff like markov chains etc also.
    thanks.

  • @pon00050
    @pon00050 13 років тому +5

    Sal
    On the website, it says "Watch. Practice. Learn almost anything for free."
    What subjects will you NOT cover?
    is foreign language one?

  • @nickbozzelli-levine6184
    @nickbozzelli-levine6184 2 роки тому

    Thank you for saving my Finite Grade!

  • @write2ruby
    @write2ruby 3 роки тому

    Very nice example

  • @samanthapikus3178
    @samanthapikus3178 7 років тому +1

    Helpful videos. You explain beautifully. I am now a little lost as in the video before this you multiplied and in this one you're adding. Please explain when does one multiply and when do you add. I can't tell the difference about when to do Multiplication and when to do addition with probability.

    • @bnv8514
      @bnv8514 5 років тому

      Do u get it now? 😂

    • @bnv8514
      @bnv8514 5 років тому

      Pls tell me the difference if u do

  • @niheltouil7513
    @niheltouil7513 4 роки тому +1

    YES, heads, that's why I failed the prob exam, they wrote head instead of heads!

  • @jubaerad2061
    @jubaerad2061 2 роки тому

    Great work.

  • @luvleyred5393
    @luvleyred5393 2 роки тому +1

    9:13

  • @therealchristian1
    @therealchristian1 3 роки тому

    you're a god!

  • @danielc4267
    @danielc4267 7 років тому +1

    Although I have figured it out, it was not immediately clear to me why multiplying 4 places by 3 places to get 12 scenarios.

  • @C0nn0isseur
    @C0nn0isseur 13 років тому +3

    The 4th one should be P(TTTH)

    • @bnv8514
      @bnv8514 5 років тому

      😂😂😂

  • @VishalSharma-nq3xr
    @VishalSharma-nq3xr 4 роки тому

    Can use combinations (permutations and combination)

  • @AayanBaloch-f2u
    @AayanBaloch-f2u 2 місяці тому

    Grade technique

  • @benhardsim8629
    @benhardsim8629 5 років тому +2

    the thing i still don't understand is why u divided all the different scenarios by 2 ?

    • @a.meforyou
      @a.meforyou 8 місяців тому

      In case anybody else is confused,
      2 ways of arranging the two heads. P(HaHbTT) is the same as P(HbHaTT). P(THaTHb) is same as P(THbTHb) is you remove the a and b and view them as identical objects. In which case P(HHTT) is the same as P(HHTT) isn't it?
      So you have to remove all the extra possiblitites. Sice we only want one of all the two scenarios we divide all scenarios by two.

  • @Fhost_G
    @Fhost_G 4 роки тому +1

    2021😁✌️

  • @perlz0
    @perlz0 13 років тому +1

    Can't you just use the binomial probability equation i.e. P(X=k)=nCk(p)^k(1-p)^(n-k)?

  • @26goldnugge
    @26goldnugge 6 років тому

    Can we tell how many times the coin has to be flipped in the set of four times to come out true for exactly one head?

  • @timothygreen158
    @timothygreen158 10 років тому

    Khan, can u do a video on stars and bars, im in 8th grade training for a math competition and I need help understanding what the stars and bars formula is.

    • @neko2000gh
      @neko2000gh 8 років тому

      Timothy Green yes please

  • @perlz0
    @perlz0 13 років тому

    @perlz0 Never mind... that's what the next video is :P

  • @ohyash
    @ohyash 5 років тому +2

    Probability of me getting a head on the first date = 0/1 = 0
    Probability of me getting a head on the nth date = (n x 0)/n = 0

  • @BraiRai
    @BraiRai 13 років тому +3

    probability of heads in 4th flip fail 2:39 ... should be "P (TTTH)" not "P (TTHT)" again

  • @TheBancho22
    @TheBancho22 12 років тому

    Actually on the video with the yellow and green cubes and spheres you made a mistake by double-counting the number of yellow cubes. How come you didn't correct it in some way?

  • @Puh539
    @Puh539 4 роки тому

    2020 anyone
    Thumb up

  • @rishujeetrai5780
    @rishujeetrai5780 5 років тому

    Not the video I was looking for ;)

  • @cappuccinocoffee9734
    @cappuccinocoffee9734 5 років тому +1

    Guys i just realize you can apply combination here

  • @rajeshraut2955
    @rajeshraut2955 4 роки тому

    I am little confused can anyone help me?

  • @ColaGrain
    @ColaGrain 10 років тому +1

    Am i the only one who hears his hard disk reading?

  • @erianadenise3145
    @erianadenise3145 8 років тому

    What grade is this

    • @Cyberw4y
      @Cyberw4y 8 років тому

      +Eriana Freeman 9th

  • @moaningmoron3703
    @moaningmoron3703 12 років тому +1

    If there's four places you can get the head in then why can I only find three places that it fits..?? :S

    • @benhardsim8629
      @benhardsim8629 5 років тому +2

      because the first place has taken by the first head ( sorry for my bad english , and i know i am 6 years late , but hopefully its gonna be useful by someone else )

  • @Hieuiph
    @Hieuiph 8 років тому

    How many coin toss to have 4 heads consecutive ?

    • @sonyvaio1281
      @sonyvaio1281 4 роки тому +1

      @@Rdffuguihug wrong, why? When you introduce a sequence/consecutive, you must also factor the condition of having a head before having another head. But independently without a prior condition of having a head then yes, it is 1/16

    • @Rdffuguihug
      @Rdffuguihug 4 роки тому +1

      @@sonyvaio1281 1/16.

    • @sonyvaio1281
      @sonyvaio1281 4 роки тому +1

      @@Rdffuguihug Am interested here, It seems I got the question wrong. This was my understanding. What would be the probability of 4 heads occurring consecutively in x number of tosses.

    • @samuraijosh1595
      @samuraijosh1595 3 роки тому

      @@sonyvaio1281 my intuition tells me P(getting four heads _consecutively_ ) should be less than 1/16. Have you figured it out????

    • @a20rahuljawale68
      @a20rahuljawale68 2 роки тому

      @@samuraijosh1595 for getting 4 consecutive heads probability will be 1/16

  • @กานต์ชนกนรดี-ธ1ฆ

    กษัตริย์

  • @harshp2577
    @harshp2577 3 роки тому

    i really frickin hate probability

    • @samuraijosh1595
      @samuraijosh1595 3 роки тому

      Just one more month for boards. You just gotta study bro....

    • @harshp2577
      @harshp2577 3 роки тому

      @@samuraijosh1595 Boards? what do you mean?

    • @samuraijosh1595
      @samuraijosh1595 3 роки тому +2

      @@harshp2577 Your name sounded Indian so I thought you were Indian and finals(boards) are coming up in march in India........

    • @harshp2577
      @harshp2577 3 роки тому +2

      @@samuraijosh1595 yea I'm indian. INDIAN AMERICAN. Gujarati specifically 😎

  • @กานต์ชนกนรดี-ธ1ฆ

    ผู้บังคับบัญชาการอธิบดีกรมคำสั่งทุกประการ