This video shows how to calculate "inside areas" and "areas in the extreme" in a normal distribution using Z-scores. This video can also be found on my website statstutor.book...
thanks for taking the time to put this together - guys like you make the world a better place by freely making education available to the masses for free - you rule!
Oisin Hughes Thank you very much. My form teacher are perfectly in knowledge however he doesn't know how to teach ,under his teaching the students cannot really understanding what is real normal distribution and only on remember the fix formula. If you remember the formula you get the score If you don't,you can't pass the exam. That was why most of the our class had failed this subject years ago.NOT on understand but on memory
After hours of laboring, and countless youtube videos, I finally got one that broke it down in bits and pieces. For one who is coming from a not too sound mathematical background, this video has been a life saver in understanding normal distributions. I'll now go ahead and tackle probability with this new found knowledge. Muchos gracias!!!
For those of you who have different charts, you're suppose to subtract the z-scores from one another instead of adding them like he does. For example, with the second problem: If you look at your chart and get .02275 for -2.00, and .97725 for 2.00; SUBTRACT them. When you subtract .02278 - .97725, you get 95.45. It isn't 95.44 but its close enough... I did the same thing with the first problem. I got z-scores .15866 for -1.00 and .84134 for 1.00. When I properly subtracted them, I got 68.26.
It's because the area for the z in your table starts from -3.5 to 3.5. Not from 0 to 3.5. For your case, just subtract .5000 of the given cumulative area. Sorry for posting this 4 years after your comment.
+Moonfall Hey as someone who has written a final on this, can you please explain the last example? He spoke about a standard rule and 3 standard deviations...what is that all about?
Muktadir Rahman Chowdhury he is using a ztable for .5 of the graph. If you have a table that shows the entire area to the left of x, you have to subtract from 1 not 0.5
WiseSloth ForBernieSanders Variance is standard deviation squared... so if variance is 36, then standard deviation is sqrt(36)=6. So mean is 5 and standard deviation is 6. The z-score for 0 is (0-5)/6= -0.83 and the z-score of 12 is (12-5)/6=1.17... so: P(0
great video, but shouldn't the z-scores be different considering one is positive and the other is negative? on the sheet i have the z-score for -2 is .0228 while the z-score for 2 is .9772. If you could clarify this issue up it'd mean a lot! thanks
R Mansour He is using a z- table of half the graph or .5 of the bell curve. If you have a table showing the full graph you would subtract from 1 not 0.5... i.e. for the last example 1-.9987 = .0013 . Your table is prob showing pvalues for all area to the left of your x. For the example you have you would take .9772 (all area to the left of 130) then you would have to subtract all area to the left of 70, which is (z score of -2) .0228 =.9544 ..... Hope that helps, I had the same issue, then realized he has a different table, for ours you have to use the pos and neg z tables.
supirior thinker, 1. plz correct your spelling first, .....2. when u feel urself superior and start to boast, u actually lose ur ability to learn more...there are still millions ideas to learn....and 3. ur bragging looks like u really learnt about "black-hole" at 15 becoz by then u started reaching adolescence...4. I learnt by heart an epic book >2000 pages "mahabharata" by 10, calculus by 8, steriochemistry by 12, Molecular medicine by 15, and completed my phd in 23.... !!! and still i am learning basic statistics becoz, i missed learning it since long !!! so fuck u !!
Americans are the most Generous People on the planet top education for free. I never meet people like you here in Germany I love America. clear and very helpful
It is the same thing really, his table represents half of the curve, while your table represents the entire curve. Hence, your 0.9773 should be subtracted from 1 = 0.0227 or 2.27%. My z value was rounded off.
so much clearer and easier to understand than coming from an old PhD professor....and the book. needless to say what i spent hours trying to comprehend I easily learned by watching this video twice. No bs. straight to the point. How teaching should be.
Excellent work. The only confusion might arise from calling the table data that you look up “distances” when they are actually the AREA under the curve. You do say area in the example where you have to subtract it from 0.5 to determine the “greater than” AREA. For those of you with the double data values, you4 chart is giving the area between the -x and +x value of the z score.. so it’s double the area.
Just wanted to say thank you! I'm in beginners Stats class and could not figure a certain problem out...random person scoring above 65%. Your instruction on IQ of greater than 130% helped me out! Thanks again!!
thanks for this!!! :D I finally understand it- although I must say, I don't really pay attention in class O.o I think I'm ready to take on more difficult examples now :D
I have my first math exam in two years tmrw and doing the textbook problems had me so stumped. I'm solving these with you and pausing so I can test myself and beat you to the next step. I'm nailing all these and feeling way more confident about not only solving the problems but also about the logic behind it all. Thanks so much for this great video :)
you are the first person I unstand. prof always keeps in algebraic form but idk what it stands for when u break it u take a hard problem make it simple
This topic can be really difficult the first time learning them, but once it clicks (Which can take a while), it's not so bad. You seem to help it click a lot more quickly than it otherwise would!
THANK YOU SO MUCH. I have a college class certification due in 4 days and this really helped me understand bell curves and standard deviation with percentages. You rock!
My poor head don't understand the concept yet , but after strolling dozens of videos , your video game high hopes , thank you , i like the steps you go through, my professor is like a hurricane !!
Thank you! This makes so much sense. My book made is seem like greek! Please post all of your teachings! Teachers like you make the world a better place.
This proves the empirical formula for bell shaped curves. 1) 68% of the population lies within 1 standard deviation of the mean. 2) 95% of the population lies within 2 standard deviation of the mean. 3) 99.7% of the population lies within 3 standard deviation of the mean.
thank you very much for your clear teaching. I will be indeed grateful if you consider my problem .let's consider the function be defined such as g(x,v) where v~N(mu = 150 , sigma=15) how can we find the P(100 - x*v)>0 ?? ... in an article author states the probability 4.29*10^-4
Hello I am really struggling with an assignment question, your video helped me a lot but I am still not getting anywhere close to the multiple choice answers for my assignment please help if you can. The books I have are gibberish and your video was the first that actually made any sense For a random variable that is normally distributed, with a population mean = 80 and a population standard deviation =10, the probability that a simple random sample of 25 items will have a mean that is between 79 and 85 is 1. 0:9938 2. 0:3085 3. 0:6853 4. 0:4997 5. 0:6835
how i do this problem? Online Books A Consumer Reports Research Center survey of 427 women showed that 29.0%of them purchase books online. a. Among the 427 women who were surveyed, what is the number of women who said that they purchase books online? b. Find a 95% confidence interval estimate of the percentage of all women who purchase books online. c. Can we safely conclude that less than 50% of all women purchase books online? Why or why not? d. Can we safely conclude that at least 25% of all women purchase books online? Why or why not? e. What do the results tell us about the percentage of men
Thank you for given those knowledge on video and for explain materials, very insightful. Hoperfully can added more knowledge and help us on the college process for subject : Operating Research. God Bless us.
The percentage of dislikes to likes for this video at this moment is 234 out of 5.7K or 4.1% lying outside 2 standard deviations or 100 - 2 x 47.72 = 4.56% ! Meaning the dislikers are insignificant critics to this well-made video. Thanks pspollard1 !
7. In an industrial process the diameter of ball bearing is an important component part. The buyer sets specification on the diameter to be 3.0 +͟ 0.01 cm. the implication is that no part falling outside these specification will be accepted. It is known that in the process the diameter of ball bearing has normal distribution with mean 3.0 and standard deviation = 0.005. On the average, how many manufactured ball bearing will be scrapped?
Since you went out of your way to mention that people with IQs above three standard deviations from the mean are officially geniuses, it begs the question: if someone has an IQ below 55 (i.e. more than three standard deviations below the mean), what is the scientific name for people in that group? They're also in the 0.13% club, meaning they´re just as infrequent as geniuses according to this model. Shouldn't we be thinking of them and their situation as well?
2:19 I might be wrong, but I think the entry in the table represents the area under the curve (the percentage of the total 1 under the curve ) if Z-score=1 rather than the "Z-score". Consequently, in the following graph, 0.3414 should not be present as a distance, but an area.
The average score on an IQ test is 100. Most people fall within the 85 to 114 range. Any score over 140 is considered a high IQ. A score over 160 is considered a genius IQ.
Thank you! You made it simple to understand. The CFA study guide made used 900 variables and made it so impossible to understand. Could have explained what the z score and z table mean in one sentence.
I understood everything except how you got the standard deviation of 15, do we need a formula for that? My proffesor used some formula that had something being divided by N-1 and I'm so confused about it!
you explained what my professor (who has a phd and whos been published dozens of times) could not. Sir, I tip my hat to you, and id like to buy you a beer (if your ever in the area). Many thanks.
Those who use the normal distribution should always be aware that the independent values range from -infinity to +infinity. In reality, nothing has this range.
Those who use the normal distribution should always be aware that the independent values range from -infinity to +infinity. In reality, nothing has this range.
thanks for taking the time to put this together - guys like you make the world a better place by freely making education available to the masses for free - you rule!
overpriced academia be like "THEY TOOK OUR JOBS!"
Oisin Hughes stay blessed
Oisin Hughes
Thank you very much.
My form teacher are perfectly in knowledge however he doesn't know how to teach ,under his teaching the students cannot really understanding what is real normal distribution and only on remember the fix formula.
If you remember the formula you get the score
If you don't,you can't pass the exam.
That was why most of the our class had failed this subject years ago.NOT on understand but on memory
Oisin Hughes this had shows the difference way on the teaching.
Instead of memory teaching.make students understand are more helpful.Thanks you again
ruclips.net/video/029laWCUOj4/видео.html
whos here for tomorrow's exam
lol me
me grade 9 student huhuhu
ME ME
hahahahah me
SAMEEEEE
thank you, this helped so much. i can not explain how glad i am i found this video
Thank you sooooo much! This makes a lot more sense than it did in class.
Thanks for this explanation...
omg.......this is so helpful.thanks
brilliant! well explained.
if i have a median of 21.8 and a varient of 1 how do i create a graph to show the the area between 19-24 ?
which table is that because othe one im using says 1.0 = 0.8413, im confused
Hey Rushee, were you able to figure it out? My table also says 0.8413.
thank you!
Way easier to understand than my stats prof
+GoldenArrow AGREED
thank you!
I love how you did it multiple times. Its 1 million times better than other vids when they just show you once. This really gets it through your head.
your head! It like most degrees are apparent to me before doing them!
After hours of laboring, and countless youtube videos, I finally got one that broke it down in bits and pieces. For one who is coming from a not too sound mathematical background, this video has been a life saver in understanding normal distributions.
I'll now go ahead and tackle probability with this new found knowledge.
Muchos gracias!!!
this is honestly what I look for in a online math video , no rambling... you nailed it.
For those of you who have different charts, you're suppose to subtract the z-scores from one another instead of adding them like he does. For example, with the second problem: If you look at your chart and get .02275 for -2.00, and .97725 for 2.00; SUBTRACT them. When you subtract .02278 - .97725, you get 95.45. It isn't 95.44 but its close enough...
I did the same thing with the first problem. I got z-scores .15866 for -1.00 and .84134 for 1.00. When I properly subtracted them, I got 68.26.
Thank you so VERY much for this comment! I was going crazy trying to figure out why I couldn't get the same answer!!
i am fucked for this exam god damnit
How come the Z table I was given in class is different ? at 1.00 on my Z tableI have .8413
i got that allso that value but i did i the sci cal...not actually on z table
It's because the area for the z in your table starts from -3.5 to 3.5. Not from 0 to 3.5.
For your case, just subtract .5000 of the given cumulative area.
Sorry for posting this 4 years after your comment.
same
AJ Radaza lmaoooo 🤣🤣🤣🤣🤣
@@AJRadaza no thanks for posting this.I am having problems and this was helpful...but mine starts from _3.0
This is a miracle. I didn't get this until I watched your video and my final is tomorrow morning. XD thanks for sharing!
how did your final go?
+Moonfall Hey as someone who has written a final on this, can you please explain the last example? He spoke about a standard rule and 3 standard deviations...what is that all about?
I'm in the exact same position, 6 years later XD
Everybody talking bout there professors wtf This my senior year in high school and gotta work on this shit
same
your Z score table is different.. my 1 is 0.8413
same here
that's because you're using the one for cumulative probabilities
no actually im using the z table for normal distributions
ok my book has both
.3413 is from negative z table for -1.00
Straight forward, simple, no unneeded explanations. Just what I was looking for. Thank You
why am i learning this.. i'm gonna drop out of college and be a billionaire.
NotoriousNkz What dumb fuck studies this in college, im in junior high school and this is basic for me
@@patrickreaport7967 ah shit. I'm dumb fuck along with all the other dumb fucks doing undergrad courses.. man.. if only we were as smart as you...
Land Nostalgia • 3.4M views wow ur a genius prodigy superhuman
Are you by any chance using a wrong table?
Muktadir Rahman Chowdhury he is using a ztable for .5 of the graph. If you have a table that shows the entire area to the left of x, you have to subtract from 1 not 0.5
Matthew Matlock I need help please!
I have a question that says mean is 5 and Variance is 36 in a normal distribution.
what is the P(0
WiseSloth ForBernieSanders Variance is standard deviation squared... so if variance is 36, then standard deviation is sqrt(36)=6. So mean is 5 and standard deviation is 6. The z-score for 0 is (0-5)/6= -0.83 and the z-score of 12 is (12-5)/6=1.17... so:
P(0
i finally understand how to apply the information from class. thank you so much
te iban a raspar con esa materia.
Ivan Burgos iban... jejeje ahora no
Dios te bendiga muñeco
clear as hell, i was doing CFA level 1 test and struggling with normal distribution! your lecture is amazing.. it helps a lot, thx buddy
My teacher was explaining this to the class for around 2 classes and most of us didnt get it. This video is the best!
whos watching in 2019 in stats class? xD
oh my god me!!!! \(^0^)/
great video, but shouldn't the z-scores be different considering one is positive and the other is negative? on the sheet i have the z-score for -2 is .0228 while the z-score for 2 is .9772. If you could clarify this issue up it'd mean a lot! thanks
R Mansour He is using a z- table of half the graph or .5 of the bell curve. If you have a table showing the full graph you would subtract from 1 not 0.5... i.e. for the last example 1-.9987 = .0013 . Your table is prob showing pvalues for all area to the left of your x. For the example you have you would take .9772 (all area to the left of 130) then you would have to subtract all area to the left of 70, which is (z score of -2) .0228 =.9544 ..... Hope that helps, I had the same issue, then realized he has a different table, for ours you have to use the pos and neg z tables.
Thank you for the detailed explanation, Matthew.
Matthew Matlock that really helps!!
@@matthewmatlock4484 thank you so much for taking time to solve my issue too. Im also using full pvalue table
I like this explanation. It's simplified and dummy-friendly.
supirior thinker, 1. plz correct your spelling first, .....2. when u feel urself superior and start to boast, u actually lose ur ability to learn more...there are still millions ideas to learn....and 3. ur bragging looks like u really learnt about "black-hole" at 15 becoz by then u started reaching adolescence...4. I learnt by heart an epic book >2000 pages "mahabharata" by 10, calculus by 8, steriochemistry by 12, Molecular medicine by 15, and completed my phd in 23.... !!! and still i am learning basic statistics becoz, i missed learning it since long !!! so fuck u !!
Very good explanation but in 7.29 how did he know that St.Dev 15 is .5000? Please explain to me if someone knows, thanks in advance!
Americans are the most Generous People on the planet top education for free.
I never meet people like you here in Germany
I love America.
clear and very helpful
Yes, our education system is awesome because we give financial aid to people that can't afford school :) Most of us are generous with knowledge too.
supirior thinker how are u so rude to ppl when youtube name is spelled wrong? humble yourself and stop with the negativity
It is the same thing really, his table represents half of the curve, while your table represents the entire curve. Hence, your 0.9773 should be subtracted from 1 = 0.0227 or 2.27%. My z value was rounded off.
so much clearer and easier to understand than coming from an old PhD professor....and the book. needless to say what i spent hours trying to comprehend I easily learned by watching this video twice. No bs. straight to the point. How teaching should be.
though everything becomes old math never, anyway nice examples sir
im here because i need to teach my sister this shit and she's like on her phone right now doing shit ughhhhhh saaaaave meeeee
Excellent work. The only confusion might arise from calling the table data that you look up “distances” when they are actually the AREA under the curve. You do say area in the example where you have to subtract it from 0.5 to determine the “greater than” AREA. For those of you with the double data values, you4 chart is giving the area between the -x and +x value of the z score.. so it’s double the area.
You are right. It is formally called "area under normal curve"
Hi Sir,
Kindly explain why do we subtract 0.5 instead of 1? What happens to the other portion in the left, don't we consider that?
I have the same problem because my lecturer taught table value should be subtracted by 1 🤔
You're a life saver! Been studying for final and was having issues until watching your video. THANK YOU.
thank you bro! i need this tomorrow for my exams
thanks so much. learn more in this ten minutes than class for the last two weeks
thank you sir....I salute
Thankyou for the video, it really helped to how this precisely and clearly
Just wanted to say thank you! I'm in beginners Stats class and could not figure a certain problem out...random person scoring above 65%. Your instruction on IQ of greater than 130% helped me out! Thanks again!!
Really great explanation. I wish I would've seen this video before I crashed and burned on my test :/ But thanks for putting this up. Super helpful!
omg hes saved my life! i was freaking out about my exam coming up
thanks for this!!! :D I finally understand it- although I must say, I don't really pay attention in class O.o I think I'm ready to take on more difficult examples now :D
I have my first math exam in two years tmrw and doing the textbook problems had me so stumped. I'm solving these with you and pausing so I can test myself and beat you to the next step. I'm nailing all these and feeling way more confident about not only solving the problems but also about the logic behind it all. Thanks so much for this great video :)
you are the first person I unstand. prof always keeps in algebraic form but idk what it stands for when u break it u take a hard problem make it simple
This topic can be really difficult the first time learning them, but once it clicks (Which can take a while), it's not so bad. You seem to help it click a lot more quickly than it otherwise would!
THANK YOU SO MUCH. I have a college class certification due in 4 days and this really helped me understand bell curves and standard deviation with percentages. You rock!
My poor head don't understand the concept yet , but after strolling dozens of videos , your video game high hopes , thank you , i like the steps you go through, my professor is like a hurricane !!
such a wonderful video! thanks a lot
Thank you for explaining this so clearly!
Thank you! This makes so much sense. My book made is seem like greek! Please post all of your teachings! Teachers like you make the world a better place.
I was in a 3 hour lecture at uni not being able to understand it at all and you explained it in 10 minutes.... impressive ! Thank you so much.
who else is here 2 hrs after the exams. Thuglife😎🔫
grace wakesho are you by any chance from Philippines?
This professor is so awesome that Majority of people can understand Z score calculations within 10 minutes :)
This guy is so good and I'm learning this stuff in my sophomore year
Of high school
Thank you SO SO MUCH!!! It was of greater than great help!❤
Finally understood how this works!!! THANK YOU SO MUCH!
Thank you so much! My final exam is in 30 mins and you’ve made this really clear for me!
finals in about 2 hours and you made more sense in 10 mins than my lecturer in 3 months - thank youuu
why is your table given numbers different from mine? :(
thank you so much. this video has helped me heaps. i didnt understand this at all until i watched this. great information
I check many standard normal z tables and all get different number than that u use !!
+abdulrahman alkadhi There is different z tables: you should be aware of the alpha level
+abdulrahman alkadhi Some z tables are for Left side some for right side you have to use right type of table by seeing your Bell Diagram
As Joe Pesci said: _"Thank you very, _*_very_*_ much!"_
This proves the empirical formula for bell shaped curves.
1) 68% of the population lies within 1 standard deviation of the mean.
2) 95% of the population lies within 2 standard deviation of the mean.
3) 99.7% of the population lies within 3 standard deviation of the mean.
thank you very much for your clear teaching. I will be indeed grateful if you consider my problem .let's consider the function be defined such as g(x,v) where v~N(mu = 150 , sigma=15) how can we find the P(100 - x*v)>0 ?? ... in an article author states the probability 4.29*10^-4
ANILAYATI
NIM : 044058927 , materi sangat jelas dan mudah dipahami.
Hello I am really struggling with an assignment question, your video helped me a lot but I am still not getting anywhere close to the multiple choice answers for my assignment please help if you can. The books I have are gibberish and your video was the first that actually made any sense
For a random variable that is normally distributed, with a population mean = 80 and a population standard deviation =10, the probability that a simple random sample of 25 items will have a mean that is between 79 and 85 is
1. 0:9938
2. 0:3085
3. 0:6853
4. 0:4997
5. 0:6835
how i do this problem?
Online Books A Consumer Reports Research Center survey of 427 women showed that 29.0%of them purchase books online.
a. Among the 427 women who were surveyed, what is the number of women who said that they purchase books online?
b. Find a 95% confidence interval estimate of the percentage of all women who purchase books online.
c. Can we safely conclude that less than 50% of all women purchase books online? Why or why not?
d. Can we safely conclude that at least 25% of all women purchase books online? Why or why not?
e. What do the results tell us about the percentage of men
Thank you for given those knowledge on video and for explain materials, very insightful.
Hoperfully can added more knowledge and help us on the college process for subject : Operating Research. God Bless us.
The percentage of dislikes to likes for this video at this moment is 234 out of 5.7K or 4.1% lying outside 2 standard deviations or 100 - 2 x 47.72 = 4.56% ! Meaning the dislikers are insignificant critics to this well-made video. Thanks pspollard1 !
7. In an industrial process the diameter of ball bearing is an important component part. The buyer sets specification on the diameter to be 3.0 +͟ 0.01 cm. the implication is that no part falling outside these specification will be accepted. It is known that in the process the diameter of ball bearing has normal distribution with mean 3.0 and standard deviation = 0.005. On the average, how many manufactured ball bearing will be scrapped?
oh how I wish my teacher did this.... Instead he just talks. I NEED TO SEE IT! PROFESSORS! SHOW YOUR STUDENTS! HEEEEELLO! Good job!
question how would i find value of c if i have mean= 3.6 and Stndrd div of 0.1 of p(-c
Since you went out of your way to mention that people with IQs above three standard deviations from the mean are officially geniuses, it begs the question: if someone has an IQ below 55 (i.e. more than three standard deviations below the mean), what is the scientific name for people in that group? They're also in the 0.13% club, meaning they´re just as infrequent as geniuses according to this model. Shouldn't we be thinking of them and their situation as well?
lmao this guys would save me soo much money instead of going to school
2:19 I might be wrong, but I think the entry in the table represents the area under the curve (the percentage of the total 1 under the curve ) if Z-score=1 rather than the "Z-score". Consequently, in the following graph, 0.3414 should not be present as a distance, but an area.
This helped refreshed my memory! Have a final tomorrow
ubsurd calculations, don't reflect reality
Learn 1month teaching lessons in 10minutes Great!
The average score on an IQ test is 100. Most people fall within the 85 to 114 range. Any score over 140 is considered a high IQ. A score over 160 is considered a genius IQ.
Excellent. This example can be replicated in any set of scores - including employee performance , Ranking of companies in revenue performance, etc.
Thank you! You made it simple to understand. The CFA study guide made used 900 variables and made it so impossible to understand. Could have explained what the z score and z table mean in one sentence.
I understood everything except how you got the standard deviation of 15, do we need a formula for that? My proffesor used some formula that had something being divided by N-1 and I'm so confused about it!
Thank you so much for making this video, it was really helpful to prepare for my exam. Now I can say I understand Z-scores XD
Is it too much to ask for additional examples? This was BEYOND GREAT and something I haven't seen that goes straight to the point!
you explained what my professor (who has a phd and whos been published dozens of times) could not. Sir, I tip my hat to you, and id like to buy you a beer (if your ever in the area). Many thanks.
What exactly is Rotogenflux Methods? How does this thing really work? I see many people keep on speaking about this intelligence boost system.
Bless your soul Man, you just saved me
have a test tomorrow and this video just saved my life
This is a miracle. I didn't get this until I watched your video and my final is tomorrow morning. XD thanks for sharing!
Wouldn't the z-score actually denote the area under the curve between the mean and x1/x2 instead of the distance? Or did I mix up concepts here?
Tnx u I really Benefit on this lecture sir....
Those who use the normal distribution should always be aware that the independent values range from -infinity to +infinity. In reality, nothing has this range.
Those who use the normal distribution should always be aware that the independent values range from -infinity to +infinity. In reality, nothing has this range.
i don't know why but in my table for the value of z 2.0 is 0.9772 and same goes for others..please help
Should you add or subtract when you are given a problem of "between"? Some teachers stated different kinds of methods.