Permutations

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  • Опубликовано: 8 дек 2024

Комментарии • 287

  • @ガジュマル-s1f
    @ガジュマル-s1f 6 лет назад +7

    My statistics professor is someone who explains things for people who already know about the topic.
    There are variables everywhere which are not explained.
    Thank you for making this video, it showed me how simple this actually is and how fun the topic can be.

  • @gwiough1656
    @gwiough1656 10 лет назад +133

    In behalf of all the people cramming for their finals right now, thank you!

    • @Clammychow
      @Clammychow 7 лет назад +6

      And here I am, three years later. My final's tomorrow XD

    • @avory7938
      @avory7938 3 года назад +3

      @@Clammychow and here I am, 3 years later. My final's tomorrow xD

    • @radd4255
      @radd4255 2 года назад +2

      @@avory7938 Here I am, a year later. My final is tomorrow.

    • @yamboyasmr4779
      @yamboyasmr4779 Год назад +2

      @@radd4255 I'm here a month later finals tmr

    • @ivanmartincampoy
      @ivanmartincampoy Год назад +2

      @@yamboyasmr4779 i'm here a month later as well

  • @EricaMorgan
    @EricaMorgan 8 лет назад +130

    Whhhhhyyyy doesn't my genetics professor teach it this way??? the formula is so confusing, but the way you explained it I understood it and it's so easy!

  • @esperar1
    @esperar1 12 лет назад +5

    This is currently the clearest video I've found on permutations. It actually explains the concept behind the equation, which will stay in my understanding far beyond the memory of the equation. Thanks!

  • @Tosserke
    @Tosserke 12 лет назад +1

    I use these videos for my exams at university, just love this. It's no drama if I skip a class, this is taught even better

  • @maitrigandhi51
    @maitrigandhi51 7 лет назад +9

    This is so EASY. I have an exam tomorrow and I'm relying on this video for 5 marks! Extremely helpful!!

  • @adamdintelman2067
    @adamdintelman2067 8 лет назад +99

    Holy shit, this guy does everything! I mean seriously, what can'd he do?

  • @acatindisguise
    @acatindisguise 8 лет назад +8

    you explained it better than the lecturer at school. thanks for this video :)

  • @shekelboi
    @shekelboi Год назад +1

    For others viewing the video:
    at 8:00 please note that the factorial symbol should be outside the parenthesis:
    n!/(n-k)!

  • @TechLord79
    @TechLord79 10 лет назад +6

    Thank you very much, when I learned that at school back then they went over it too fast and I could not get the reasoning behind the formulas. I see clearly now, well presented :-)

  • @balsyitlog
    @balsyitlog 11 лет назад

    Thank you khan for always bringing me one step closer to smartness.

  • @moneychica
    @moneychica 12 лет назад

    THANKS! These are great tutorials, I'm currently doing online schooling and my cousin just recommended you.

  • @aerismagia8058
    @aerismagia8058 8 лет назад +13

    I would like to see Sal teach electrical engineering.

  • @farenkofi
    @farenkofi 9 лет назад +6

    I am very grateful for the explanation and logical reasoning. The basic concept is what i really needed and that it something i didn't have while doing additional math for IGCSE. I'm happy nonetheless I have understood in A level statistics. Thank you.

  • @scoldingMime
    @scoldingMime 11 лет назад +2

    "And I want to know, how many different ways can I put these 3 balls into these 2 cups?"
    Call me immature, but I started chuckling.
    Aside from that, this was very informative.

  • @LAnonHubbard
    @LAnonHubbard 14 лет назад +1

    Good explanation. I've always found this sort of thing confusing but this video was very clear. Great intuition gained.

  • @heldan898
    @heldan898 11 лет назад +19

    3 balls, 2 cups

  • @ThomasMendenhall
    @ThomasMendenhall 11 лет назад

    You are the reason I survived 6th grade. thanks for making these videos.

  • @aaaasssskkk11111
    @aaaasssskkk11111 12 лет назад

    THANK YOU THANK YOU THANK YOU!!!!! I have a probability test next peroid, and didn't get it until I watched this!!!!!

  • @seemade4432
    @seemade4432 6 лет назад +3

    In India permutations is taught in class 11 & 12 but due to this awesome guy I understood the topic even after being in class 9 . Thanks Sal

  • @thelamp091
    @thelamp091 3 года назад +1

    It is a video from many years before bir it's still very helpul. Thank you so much!

  • @dennisphieros7266
    @dennisphieros7266 10 лет назад +15

    Khan Academy rules...

  • @levizraelit5557
    @levizraelit5557 10 лет назад

    Thank you so much. I've spent an entire day trying to understand this from the textbook with no success.

  • @jugsmcflugs4954
    @jugsmcflugs4954 7 лет назад +5

    I learn more from this than my geometry teacher

  • @ronroyes2375
    @ronroyes2375 7 лет назад

    I usually don't understand his vids, but he taught this so easily... even I could grasp the concept this time 😅

  • @Mslokalove
    @Mslokalove 9 лет назад +6

    You're a life saver!!❤❤❤

  • @abdullaprobably
    @abdullaprobably Год назад

    Wow this style of teaching is soo good

  • @Death_User666
    @Death_User666 7 лет назад

    i am in college and i am learning this all on my own thanks to this guy

  • @anshikakushwaha3150
    @anshikakushwaha3150 6 лет назад +1

    2018!? Time flies fast. 2008 passed 10 years back!

  • @Swiizzey
    @Swiizzey 9 лет назад +73

    7:58 I feel bad for people watching this on mobile and not being able to see the annotation correction and get really confused

    • @eliaskountouris4214
      @eliaskountouris4214 7 лет назад +9

      Swiizzey what I'm on mobile pls help

    • @jugsmcflugs4954
      @jugsmcflugs4954 7 лет назад +7

      Elias kountouris equation is supposed to be n!/(n-k)!

    • @advaitpai1615
      @advaitpai1615 7 лет назад +6

      DeformedBear who the hell allows phones into examination halls

    • @suneelnadipalli2685
      @suneelnadipalli2685 7 лет назад +6

      Sal wrote n!/(n-k!)
      It's supposed to be n!/(n-k)!

    • @troyawaneedavisd
      @troyawaneedavisd 6 лет назад

      Swiizzey And I certainly did get confused!! Thumbs down for me!!

  • @aditishikha8149
    @aditishikha8149 4 года назад +1

    Great work sir. Thanks for making me understand this thing so easily.

  • @farouku5334
    @farouku5334 5 лет назад +1

    old but gold

  • @mariapineyrua5405
    @mariapineyrua5405 8 лет назад

    you are the best! i been using your videos since I was in remedial at college, know I'm in my last year of the university. doing qmb. you should be a professor! thanks

  • @AishLovesSpaghetti
    @AishLovesSpaghetti 4 года назад

    You explained everything very cleary using easy practical examples. Keep up the good work!

  • @somber_soul
    @somber_soul 13 лет назад

    @moka22051 A factorial is when you multiply that number by all the positive integers below it. For example, 7! is 7*6*5*4*3*2*1.

  • @rtoriq
    @rtoriq 12 лет назад

    i'm with you 100%, bc it irritates me how NO ONE, not even textbooks explain how you just up and multiply. The reason you multiply is just think of what multiplication represents: groups. 7x6 means 7 groups of 6 (or 6 groups of 7). That gives you 42, either way. 3 groups of 2 (or 2 groups of 3) give you 6. Well, if you have say, 4 balls (A, B, C, D) and 3 cups, for your FIRST choice of A, there's 6 ways -6 groups of choices- to fill the 3 cups IF you're starting your choice with A....

  • @sureshchaudhari4465
    @sureshchaudhari4465 4 года назад

    Hi I was very weak in maths I wish internet was super cheap in my academic years I would have got better marks and understanding about maths concepts.Thanks Khan Academy

  • @rahafhesham3262
    @rahafhesham3262 4 года назад +5

    me in 2020 tryna understand this topic cause online school doesn't help

  • @Littlechonch
    @Littlechonch 9 лет назад +1

    Oh my god thank you so much our teacher has literally taught us nothing about this and has told us to research it for our assignment this helped so much

    • @ucHorrible
      @ucHorrible 9 лет назад +1

      Mine did, too! It was the last lesson in the chapter, too xD

    • @ucHorrible
      @ucHorrible 9 лет назад

      ***** 8

    • @Littlechonch
      @Littlechonch 9 лет назад

      HermitOfTheFragshack Oh you poor soul I'm in grade 10

    • @Diegoangola1
      @Diegoangola1 9 лет назад

      +HermitOfTheFragshack me too

  • @legendinbusiness2022
    @legendinbusiness2022 7 лет назад

    Thanx khan academy for making the impossible possible coz i am just studying in9th standard and i need to write an olympiad based on 16 chapters which includes combinations and permutations. And now may be i will achieve a good rank in it.

  • @const71
    @const71 8 месяцев назад

    great explanation ... a good analogy might be scrabble tiles on the rack played on the board squares...

  • @ozzyfromspace
    @ozzyfromspace 6 лет назад

    Wig snatched. Thanks Sal, I needed this refresher (found an application for it in my research so many years later lol).

  • @pzsmcrew
    @pzsmcrew 15 лет назад

    THANK YOU REALLY MUCH, I have tomorow big math exam, it helped me a lot

  • @Diegoangola1
    @Diegoangola1 9 лет назад +3

    Thank You, actually i had a Pre-Algebra book and i couldnt understand it, but with the video i could

  • @samanthamanego2923
    @samanthamanego2923 7 лет назад +1

    Been sitting in a chair for 2 hours, but I've never understood it. Now, 10 minutes and I have understood at least a tinsy bit.

  • @1337w0n
    @1337w0n 12 лет назад

    Its a drawing pad. You'll also need screen recording software, video editing software, and voice recording software. And a mike. I'm not sure if that software should come with either the mike or the pad.

  • @anandsivadoss
    @anandsivadoss 11 лет назад

    Quality is a concern over here when you watch online. But if you download the same & watch it with VLC player, clarity is superb...:)

  • @amirisma7972
    @amirisma7972 3 года назад

    the quality of the video is amazing

  • @IGzzyderWhizzy
    @IGzzyderWhizzy 11 лет назад

    There are 7 ways of selecting the first person to sit, and FOR EACH way out of the 7 ways, there are 6 ways of selecting the second person. Thus far there 7 * 6 ( = 42) ways of selecting the first two persons and sitting them. Again FOR EACH of the 42 possible ways of selecting the first two persons, there are 5 choices for the third sitter. Eventually we have 42 * 5 ways of selecting 3 out of 7 persons to sit.

  • @Ryoroyzu
    @Ryoroyzu 15 лет назад

    @jarrasoma
    Well, given i.e. 5 cups and 3 balls - and you put one ball in one cup - you'd have this;
    Cup 1: Ball A
    Cup 2: Ball B
    Cup 3: Ball C
    Cup 4: No ball
    Cup 5: No ball
    Now, there's a problem with our ascertion. Can you see it? The question now is better answered as a relation; In how many ways can you place a cup and a ball together? That way, the places would be the "k", and the other relation would represent the "n".

  • @axelthefuccboi764
    @axelthefuccboi764 7 лет назад

    I'm doing this in 7th grade SOO... This is REALLY helpful

  • @escodrumer
    @escodrumer 11 лет назад

    Great video!! keep it up... better than my math teacher

  • @TheDailyCat101
    @TheDailyCat101 11 лет назад

    Thank You your videos are awesome for online school.

  • @grand_tp
    @grand_tp 6 лет назад +2

    At 7:55 , it is n!÷(n-k)!

    • @logicool2793
      @logicool2793 5 лет назад

      Гленн Борс you sir are correct. please note everyone. it is NOT n!/(n-k!)

  • @abhishekravindra4008
    @abhishekravindra4008 6 лет назад

    I got intuitive blast after watching this it made so much sense looking at the angle from that you want the first k terms of the n! Then its almost common sense that you want to cancel out the left terms so you are doing (n-k)! To cancel them (n-k) is number left from n after occupying n spots

  • @bhyll2489
    @bhyll2489 11 лет назад

    this guys lessons are awesome

    • @TORAH4TEENS
      @TORAH4TEENS 4 года назад +1

      Yeah dey ma be techen stu nonsence

  • @loverofbeats
    @loverofbeats 14 лет назад

    please do combinations with repetition! it would be greatly appreciated! :D

  • @brianbernal8064
    @brianbernal8064 11 лет назад

    Better than my math teacher

  • @medo5101
    @medo5101 9 лет назад

    Wonderful Explanation !

  • @scaredyghosts
    @scaredyghosts 7 лет назад

    I just found a link of his RUclips channel in my textbook...I mean I love videos so I got curious. And I don't regret I did that.

  • @aimenwaseem7854
    @aimenwaseem7854 10 лет назад

    omg thank you so much i might just pass my public exam with this (":

  • @Technikplayzzz
    @Technikplayzzz Год назад

    thanks Khan your vid's help so much ☺☺☺

  • @mohitshresthanep
    @mohitshresthanep 11 лет назад

    Thanks for the subtitles, kid.

  • @malbagashi
    @malbagashi 11 лет назад

    Thankyou sir I really respecte what you for us Teens and Kids

  • @SuPeRm4n100
    @SuPeRm4n100 14 лет назад

    idk how you know so much...thanks alot man!! :) really helped

  • @valsastephen9054
    @valsastephen9054 8 лет назад

    Reason for multiplying eg you want to go from A --B--C,with three possible routes to B and from B 4 ways to C.for every route to b there are 4 ways to C.total =3*4=12 ways for A to C

  • @madhuc52
    @madhuc52 4 года назад

    I look at this in a much simpler way as below
    " 3 chairs and 7 people"
    First spot could be fitted in 7 different way or people in this case.
    For this 7 different ways of first position there will be 6 different way remaining 6 people can occupy hence 7*6 ways two chair get filled, now again third chair has 5 left over people from each outcome (7*6 total outcomes ). So these 5 will occupy in 5 different way with total outcome of first two chair i.e (7*6)*5. If one more chair is there again we have 4 different ways remaing 4 can be associated with this all possible outcome. By THE WAY mathes is too difficult to explain or visualise through words. Happy learning.

  • @cherrylouvillas6769
    @cherrylouvillas6769 5 лет назад +2

    I'm here in preparation for my licensure examination.😆

  • @bagitandbinit
    @bagitandbinit 12 лет назад

    this video is such a great help, thank you

  • @shazaduh
    @shazaduh 15 лет назад

    keep it up! please continue with stat and prob videos

  • @freeman5860
    @freeman5860 Год назад

    an oldie but a goodie

  • @frankthetank1285
    @frankthetank1285 14 лет назад

    Thanks, your videos are always great!

  • @aal2002
    @aal2002 5 лет назад

    Thank you for making this so understandable!

  • @captainspiwtf
    @captainspiwtf 15 лет назад +1

    Chair tree? LOL Nice stuff.

  • @tanutalwar7088
    @tanutalwar7088 2 года назад

    Here in 2022, best lectures👍

  • @itzoUSA
    @itzoUSA 15 лет назад

    Very well explained!

  • @liliacfury
    @liliacfury 6 лет назад

    The first person that makes sense.

  • @anjalidutta8471
    @anjalidutta8471 7 лет назад

    Hey, I think you should put that factorial sign of k outside the braces in 8:04

  • @satisfiction
    @satisfiction 8 лет назад +1

    So in Braille there are 6 spaces... how many unique characters are there then? Because space 1 and space 2 being filled is the same as space 2 and space 1. Would it just be binary then? 2^6?

  • @junkheadrooster
    @junkheadrooster 12 лет назад

    oh thank you. real kind of u mr. old guy.

  • @aminaharis4384
    @aminaharis4384 5 лет назад

    You save my life thank you so much really

  • @rianarang5207
    @rianarang5207 8 лет назад

    This helped me a lot!

  • @gamerstormz67
    @gamerstormz67 13 лет назад

    @ninjaturtle205 lol a brown ball n yello ball too and he puts them on the cups!

  • @harshgog8212
    @harshgog8212 12 лет назад

    Thankss KA!! gosh ur the bestt!! i totally understand this now!!

  • @oxford_phd
    @oxford_phd 12 лет назад

    "Bee in kap one, cee in kaptu, ay in kupwun, bee in kuptu.. " At 3:52 he sounds chinese to me ;)

  • @abidnoushad2883
    @abidnoushad2883 6 лет назад

    Thank you 👍

  • @ZelForShort
    @ZelForShort 7 лет назад

    So if u have 7 traits, and 2 alleles/ possibilities for each trait. to calculate the possible combinations for 7 traits you would have 14 different​ traits/people. So your trying to seat 14 different people in 7 chairs/traits so? 14 x 13 x 12 x 11 x 10 x 9 x 8?

  • @kokonnichiwa
    @kokonnichiwa 9 лет назад

    thank you, i understand more now.

  • @marianfrac1569
    @marianfrac1569 8 лет назад +2

    how many 4-digit numbers can be formed from the digits 1,3,5,6,7,8 & 9 if no repetition is allowed?
    help pls

  • @raees2046
    @raees2046 8 лет назад

    how many four digit no with diff digit can be formed if unit and thousands digit must be prime?

  • @ralpharances
    @ralpharances 7 лет назад

    what do you mean by w/o restriction? example?

  • @robertbutcher222
    @robertbutcher222 8 лет назад

    In the first example with the 3 chairs why would we use npr? Npr is for when order manners. How does order manner here???

  • @gwyneabundo5423
    @gwyneabundo5423 6 лет назад

    This helped me allot!

  • @maddiericke1793
    @maddiericke1793 10 лет назад +25

    Did it bother anyone else at the beginning of the video where he didn't have a whole line over the 2? Maybe it's just my OCD again...

    • @chadfranklin47
      @chadfranklin47 9 лет назад +1

      +Chill Edits lol

    • @okcfan0217
      @okcfan0217 7 лет назад +3

      I didnt realize that until now. Thanks for making me annoyed

    • @okcfan0217
      @okcfan0217 7 лет назад +1

      The bigger problem is the unclosed six at the left center

    • @chhunchhim2546
      @chhunchhim2546 6 лет назад +1

      Yeah, It annoyed me for a sec. Then I realized, oh, he must be using a Windows XP machine. lol Man!! His videos has sure come a long way.

  • @atharvabaste4455
    @atharvabaste4455 7 лет назад

    hey sal, i'm not understanding this question (it's from iit exam)........ A train timetable must be compiled for various days of the week so that two trains twice a day depart for three days, one train daily for two days, and three trains once a day for two days. How many different timetables can be compiled?......plz answer or better make a video....

  • @NASIMBINJASIM
    @NASIMBINJASIM 12 лет назад

    thank you . @khanacademy

  • @jermam2010
    @jermam2010 7 лет назад

    What if you have just one chair and you can only fit like 4 people? Need help on this

  • @adam.phelps
    @adam.phelps 14 лет назад

    This was a great review. :)

  • @张弼-i7h
    @张弼-i7h 9 лет назад +1

    why should we multiply the 7×6×5 ?Is there any intuition explanation?

    • @pinkie24
      @pinkie24 9 лет назад +3

      +张弼 because you start with 7 people in the 1st chair. after that person sits on the first chair now you only have 6 people or choices left. thats why there are 6 people for the 2nd chair. and for the third chair you have 5 people left. Since there are only 3 chairs we stop here. thus-- 7 times 6 times 5 = 210 possibilities

    • @jsyoukr1
      @jsyoukr1 9 лет назад +3

      +pinkie24 but why not add?

    • @张弼-i7h
      @张弼-i7h 9 лет назад +1

      +DryBlue Berries That's a great question. The key points is "each" "each". As you heard that "for each of these possibilities" ,you probably can imagine that each of the 7 possibilities has another 6 new choices or possibilities. It is like that there are 7 boxes and each box "has" 6 apples, so how many apples are there ? 7 times 6, right?

    • @张弼-i7h
      @张弼-i7h 9 лет назад +1

      +pinkie24 thank you every much. After about a week of thinking and practice, I think I get it.

    • @jsyoukr1
      @jsyoukr1 9 лет назад +1

      +张弼 Hey, it seems like ur online right now. Try answering this question: A volley ball team is made up of 6 player in a line facing the camera for a picture. If Joan and Emily must be together, how many different arrangements are possible for the picture?

  • @semityyy
    @semityyy 8 лет назад

    what about putting all the ball in one cup? is that not a possible scenario