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!
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.
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!
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 :-)
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.
"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.
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
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
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
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.
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.
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....
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
@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".
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.
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
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?
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.
Out of 18 points in a plane, no three are in a straight line except 5 which are collinear. How many straight lines can be formed & how many triangles can be formed? Sir why do we need to subtract 5c3 from 18c3 in case of triangles
Please Someone tell me the Logic of multiplying ..In that balls example how do we get no. of arrangements (permutations) by just multiplying the no. of balls which will go into cups? why it gives us no. of arragements by 2 x 3 ?
If you had 12 books and 4 shelves and you'd have to arrange one book on each shelf then obviously it'd be P(12,4) = 12 x 11 x 10 x 9 but what about this problem: if you have 12 books and 4 shelves and you have to arrange all of the 12 books on these shelves, it could be 12 0 0 0, 10 2 0 0, 7 4 1 0 or whatever, how'd you solve that? thanks!
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?
what if k is greator that n, would it just be k! ? for example you are given 22 poeple 23 seats, there are 23! possibilities cause you have to factor in the situation of each time one of the seats is empty but if you had 2 or more would it stay the same or no? because tech the first and the second empty seat would be both equal seats but the 24th seat could still be sat in i just dont know.
In behalf of all the people cramming for their finals right now, thank you!
And here I am, three years later. My final's tomorrow XD
@@Clammychow and here I am, 3 years later. My final's tomorrow xD
@@avory7938 Here I am, a year later. My final is tomorrow.
@@radd4255 I'm here a month later finals tmr
@@yamboyasmr4779 i'm here a month later as well
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!
Because your genetics teacher isn't an attractive math man
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.
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!
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
you explained it better than the lecturer at school. thanks for this video :)
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 :-)
Holy shit, this guy does everything! I mean seriously, what can'd he do?
hes a alien here to help us not destroy ourselves
darius jah'skush ALL HAIL THE ALIEN WHOSE VEEN SAVING OUR GRADES!!!
he's an mitian
Adam Dintelman ikr!
Teach badly
This is so EASY. I have an exam tomorrow and I'm relying on this video for 5 marks! Extremely helpful!!
Maitri Gandhi how it went?
For others viewing the video:
at 8:00 please note that the factorial symbol should be outside the parenthesis:
n!/(n-k)!
It is a video from many years before bir it's still very helpul. Thank you so much!
THANKS! These are great tutorials, I'm currently doing online schooling and my cousin just recommended you.
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.
Thank you khan for always bringing me one step closer to smartness.
Good explanation. I've always found this sort of thing confusing but this video was very clear. Great intuition gained.
THANK YOU THANK YOU THANK YOU!!!!! I have a probability test next peroid, and didn't get it until I watched this!!!!!
I would like to see Sal teach electrical engineering.
Thank you so much. I've spent an entire day trying to understand this from the textbook with no success.
3 balls, 2 cups
7:58 I feel bad for people watching this on mobile and not being able to see the annotation correction and get really confused
Swiizzey what I'm on mobile pls help
Elias kountouris equation is supposed to be n!/(n-k)!
DeformedBear who the hell allows phones into examination halls
Sal wrote n!/(n-k!)
It's supposed to be n!/(n-k)!
Swiizzey And I certainly did get confused!! Thumbs down for me!!
I usually don't understand his vids, but he taught this so easily... even I could grasp the concept this time 😅
"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.
Great work sir. Thanks for making me understand this thing so easily.
i am in college and i am learning this all on my own thanks to this guy
You explained everything very cleary using easy practical examples. Keep up the good work!
You are the reason I survived 6th grade. thanks for making these videos.
I learn more from this than my geometry teacher
Wig snatched. Thanks Sal, I needed this refresher (found an application for it in my research so many years later lol).
Wow this style of teaching is soo good
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
old but gold
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
Mine did, too! It was the last lesson in the chapter, too xD
***** 8
HermitOfTheFragshack Oh you poor soul I'm in grade 10
+HermitOfTheFragshack me too
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
me in 2020 tryna understand this topic cause online school doesn't help
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
are you in state board ?
@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.
Thank You, actually i had a Pre-Algebra book and i couldnt understand it, but with the video i could
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.
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.
You're a life saver!!❤❤❤
2018!? Time flies fast. 2008 passed 10 years back!
Now August 2022 😌🥳
Now end of November 2023. 😌🙏
great explanation ... a good analogy might be scrabble tiles on the rack played on the board squares...
Khan Academy rules...
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....
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.
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
THANK YOU REALLY MUCH, I have tomorow big math exam, it helped me a lot
So , how was the exam?
@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".
Thank You your videos are awesome for online school.
Quality is a concern over here when you watch online. But if you download the same & watch it with VLC player, clarity is superb...:)
Great video!! keep it up... better than my math teacher
I'm doing this in 7th grade SOO... This is REALLY helpful
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.
the quality of the video is amazing
Wonderful Explanation !
this video is such a great help, thank you
Thankyou sir I really respecte what you for us Teens and Kids
Thank you for making this so understandable!
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.
this guys lessons are awesome
Yeah dey ma be techen stu nonsence
Thanks, your videos are always great!
At 7:55 , it is n!÷(n-k)!
Гленн Борс you sir are correct. please note everyone. it is NOT n!/(n-k!)
idk how you know so much...thanks alot man!! :) really helped
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
omg thank you so much i might just pass my public exam with this (":
You save my life thank you so much really
Hey, I think you should put that factorial sign of k outside the braces in 8:04
thanks Khan your vid's help so much ☺☺☺
This helped me a lot!
please do combinations with repetition! it would be greatly appreciated! :D
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?
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.
Thankss KA!! gosh ur the bestt!! i totally understand this now!!
keep it up! please continue with stat and prob videos
This helped me allot!
oh thank you. real kind of u mr. old guy.
@ninjaturtle205 lol a brown ball n yello ball too and he puts them on the cups!
Thanks for the subtitles, kid.
Thank you 👍
thank you . @khanacademy
thank you, i understand more now.
Thank you for your video!
Very well explained!
Here in 2022, best lectures👍
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
7*6*5*4= 840
Marian Frac 840
an oldie but a goodie
Better than my math teacher
I'm here in preparation for my licensure examination.😆
thx! it helped me very much!
thanks
Out of 18 points in a plane, no three are in a straight line except 5 which are collinear. How many
straight lines can be formed & how many triangles can be formed?
Sir why do we need to subtract 5c3 from 18c3 in case of triangles
Please Someone tell me the Logic of multiplying ..In that balls example how do we get no. of arrangements (permutations) by just multiplying the no. of balls which will go into cups? why it gives us no. of arragements by 2 x 3 ?
If you had 12 books and 4 shelves and you'd have to arrange one book on each shelf then obviously it'd be P(12,4) = 12 x 11 x 10 x 9
but what about this problem:
if you have 12 books and 4 shelves and you have to arrange all of the 12 books on these shelves, it could be 12 0 0 0, 10 2 0 0, 7 4 1 0 or whatever, how'd you solve that?
thanks!
In the first example with the 3 chairs why would we use npr? Npr is for when order manners. How does order manner here???
what do you mean by w/o restriction? example?
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?
what if k is greator that n, would it just be k! ? for example you are given 22 poeple 23 seats, there are 23! possibilities cause you have to factor in the situation of each time one of the seats is empty but if you had 2 or more would it stay the same or no? because tech the first and the second empty seat would be both equal seats but the 24th seat could still be sat in i just dont know.
how many four digit no with diff digit can be formed if unit and thousands digit must be prime?
The first person that makes sense.
thanks man you vids are great