Variance and Standard Deviation: Sample and Population Practice Statistics Problems

For more success with variance and standard deviation problems, you can checkout the book I used for reference, Schaum's Statistics Outline - amzn.to/2yeUaDk.
Variance and Standard Deviation are all statistical ways of measuring variation. We'll take a look at how to solve practice statistics problems for sample variance, sample standard deviation, population variance and population standard deviation by hand using just your calculator. In our problem we'll take a look at ages of kids at a birthday party. I also mention how to make meaning of this data if they were points somebody scores in various basketball games. Hope that helps.
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The videos I post on KZbin are primarily for my own college students, so I usually do not have time to respond to KZbin comments. But, I'll do my best to respond when I can.

[@Dee-ye2dk]

When you have a full time job plus attend college full time but you find someone willing to give their time to teach others via KZbin. Thank you for this video, currently taking stats in college.

[@sayedalihaider7307]

How hard could've it been for our teacher if he had just explained it this simple?! Thank you so much, man!

[@fernandomaron3498]

It's funny. Sometimes we stay 2 hours in class watching professor explain how to calculate standard deviation and variance. At the end we don't understand very well. Here, 13 min is more than enough for me to understand and gain confidence. Anyway, thank you very much for the video.

[@caseymaps4918]

That's so true

[@jasontutorials4809]

Spend time in an hour and a half lecture, and still don’t understand anything, watch a 13 min video or even shorter, and miraculously understand it...explain that

[@stephenkiama4665]

I agree with you

[@KK-yt8qw]

Stephen Kiama e

[@sirhilmohamed1193]

I seconded you.

[@AndrewMcNeillMusic]

What a brilliant communicator! Totally recommended. Look forward to checking out more of your videos

[@angelicaibanez5327]

I'm in Business Economics & Decisoin Science. Roughly over a month. I just understood your 13 min. video of the sample mean, variance, and standard deviation. Over my professor. I was struggling in finding the mean, variance and SD but i see now that is more simple then what I thought. THANK YOU!!!

[@hlalelemohale7296]

Thanks, from South Africa here sir! I have been struggling to know, when to use denominator (n-1) or 'n', you explained so clearer than cristal. Thanks now I have peace of mind, you the bosssss!!

[@elesahefner9155]

Thank you soooooo much!! I spent a week trying to understand my online stats class and watched this video 1x and now understand perfectly. YOU'RE AMAZING!!!

[@dennisecallejas7185]

ive been having a hard time understanding standard deviation and variance and am more of a hands on person when it comes to learning. Thank you very much this helped A LOT !

[@exploringim6191]

That equation looked all kinds of terrifying before you explained what the letters were. I just stared at it in my text book not understanding a single word of it. Now I'm saved. Thank you!

[@mbangetaheteng3419]

sir i really appreciate the way you teaches on this topic, you give more clarity on statistic management concerning variation,thanks

[@GrimFemme]

You just saved my grade. Thank you.

[@bismarkanloadey289]

lol funny

[@tahirhammond7032]

Sofia yh true talk

[@bismarkanloadey289]

So where do u school?

[@Leo-mh5mf]

You alive?

[@elirivera8880]

Wow ! Great explanation.... I am currently taking an online class and read the book and had no idea because the formula was driving me crazy! Thank you!

[@hanesmitter1469]

I had forgotten this simple procedure and I totally couldn't remember Credits to you

[@joyceguevara8302]

This was very helpful to understand the formulas. He make it seem very simple to do it yourself.

[@alejandrabradley8180]

Thank you for the help, great example!!

[@MathsclassKI]

very clear good teaching

[@ahamedakmal7104]

how will standard deviation of a set of discrete data change -when a value that is equal to the mean is added to data -when a value less than one standard deviation from mean is added to data -when a value that is more than one standard deviation is added to data?

[@Name_idkk]

Thank you so much. This really helped with my stat finals in a day.

[@gedeonkibambe9930]

I know that you made that video since long time, but I just wanted to say thank you for that, thanks a lot;)

[@Elviskiol-do7dy]

This explanation helps me understand very well 🙏🙏. Thank you sir🤝🤝

[@nurulainnajwasuhaimai4418]

just know that before this I'd used a complicated formula to remember. u saved my time to memorise and understand this thing!!

[@tavuzzi6955]

Thank you for your video. It did help me a lot!

[@elividal7202]

super clear explanation

[@afiacodlin3739]

i must say thank you and i so glad i came across your video. i really needed this clarification

[@nosiphosimelane5736]

I really needed this lesson before my STAs exam

[@mindy8331]

Thank you for this video. Very helpful.

[@tamaraseid7413]

I think this calculation is correct for population, but here since we have the sample of numbers so the denominator in the formula is supposed to be not n, but n-1 . Thank you for clear explanation.

[@fabishkenya9263]

great video.At least i have understood the difference between population and sample standard deviation

[@enteryunion1673]

My math teacher is not good as u sir simple yet easy to follow and understand each steps of the way.. thank u ...save. A lot of time and brain ...energy. .

[@linetgachiuki3078]

Great demonstration! I would like to be as clear as you are when I ever get to teach!

[@statisticstuber6110]

You can take any kind of statistics help at [e-mail]

[@NoNamae0_0]

bro ur a lifesaver.

[@nomarseyer4551]

simply done. Thank you

[@louiscayohwe]

I LOVE YOUR WORK SIR

[@lovemendez5406]

I loved how you described it, I was able to comprehend through your work fast, but how do you do the frequency that goes in the beginning ? Anyone please let me know thanks 🤓

[@abubakaryunusa2604]

WE ADD ALL THE FREQUENCIES AND DIVIDE THEM BY FIVE(TOTAL NUMBER OF THE FREQUENCIES) TO GET THE MEAN WHICH IS 6.4

[@yogeshpareek181]

Realy great vedio sir thax for helping

[@tarikuamante4546]

it is an interesting demonstration. you make it easy for us. thanks a lot statistic dojo

[@mrhq3153]

Good explaination.

[@af5104]

For the variance, you must divide by the total of frequencies. The square of the either of the STDEV.S and .P will not give you the variance which in most cases should be a decimal fraction.

[@sitinuradilahizzatimddaim2384]

Thank you sir.

[@smileyshine1163]

Super explanation Thank you sir

[@0069yj]

Great work ... thank you

[@penguin2106]

thank you so much. it really helps.

[@osenisuliat5041]

Thanks so much, really helpful

[@oolasaverio3756]

please I need assistance for x bar when calculating mean, the symbol is missing in my computer

[@ajayjackson7727]

what is the standard deviation of the data set 30 0 0 ?

[@peterkacheka4402]

Am asking for the interpretation please

[@user-kb6hl4kg6h]

Thank you i learn something that I didn't know before currently am from gambella region in Ethiopia county of Africa continent

[@amancabdi3035]

thank you for helping us

[@analync.torres625]

I got it. 27.2 divide by 4 is equal to 6.8. Anyway, thank you for this video. I learn a lot. God bless☺️🙏🏻

[@koba3174]

How did the 27.2 over 4 became 2.607? Did you square root it? How did you exactly got it??

[@LSAMace]

if i think this is easy will i do good in statistics class?

[@tobiasadams1504]

Thank you kind sir. Blessings.

[@toltap267]

thank for your really thinking

[@----cp6xy]

This video was so helpful 🙌

[@NaturelySpace]

Thank you

[@lekpjedits18]

Sir....plz help me to find the answer of this question : The mean and standard deviation of a set of 100 observations are worked out as 40 and 5 respectively by a computer which by mistake took the value of 50 in place of 40 for one observation. Find the correct mean and variance Plzz... bcz this is the most frequently asked question in our exams

[@danizooo2129]

can you please make a video on how to solve problems in statistics and scientific method badly need it for my psychological statistics subject

[@tammymcfee9325]

Thank you!!! I have been trying to do this for days... I have been trying to subtract the first set of x-x from the second set squared and I was always getting negatives...I was frustrated....

[@kkurachannel2715]

help... i'm cnfused with the z-score equations. how to know if a problem will use population ewuation or sample equafion..?

[@user-fb3gb2vk4e]

Thank you I'm understanding it

[@maheshwaripanuganti5889]

Thank you so much

[@jimvenniceatienda816]

ty for this video, i know how to get the variance and standard deviation

[@nakasisara4400]

I just like this class

[@angelanasto1068]

Thank you so much !!

[@Masteridea101]

undestand that, the teahcer has explained the formula.. but how is this related to the initial series??

[@farrahkhan2160]

Nice easy to understand

[@wotagetie1549]

thank you for this video

[@mikaela_reads]

THANK YOU SIR 💜

[@amancabdi3035]

we need more

[@MrOusmane23]

he is just amazing

[@celinewalters66]

Thank you!

[@taranaali6025]

Good explanation

[@eugenejoseph6666]

2.3 * 2.3 = 5.29 , round off will be 5.30 , where did you get 5.4 from ?

[@nurlatifahmohdnor8939]

Page 1 - 18 Cathode Ray Tube or The video d.: 1 Monochrome D. U. 720 dots × 348 dots (resolution) 9 × 14 dots (characters in a matrix) 2 Colour Video D.U. What are the 4 different basic colours at one time?

[@dasbodh5799]

Nice explanation 👍👍

[@naumanshabbirawan4232]

thank you so much dear sir

[@odogwuhenry]

I like your explanation. But I have one problem. Before checking out your video, I had just read a section of a book explaining standard deviation. But in the book's formula, there was no (n-1) it was just (n) and the sigma sign was written in the formula. what is the "1" for and why? It's really confusing

[@veenahebballimath5913]

Tnx for uploading this video

[@abinandankumar5283]

Why n-1 for sample to calculate Standard deviation?

[@buchayjames6948]

Thanks that's was really great

[@omiseika4104]

Hi sir I would like to ask at 12:49 why 5.4? I calculate here and it shows that 5.29

[@amanjasrotia8749]

Please clear me that why was the denominator in terms of age was n-1 where as for population it us N. Is there any more things in which n-1 is used other than N. Please clear my doubt, anyone

[@MikhaelAhava]

I think this will help me thanks.

[@hlengiwengutha7844]

Help please. A retailer observes that the demand for a popular board game averages 40 per week with the standard deviation of 13. If the seller wishes to have adequate stock 99% of the time, at least how many games must she keep on hand?

[@wynceldupal-ag3347]

Wherr do u get 5.76? I dont understand that portion

[@estherwanjiru6001]

Thank you sir

[@kaleemkhankhan6702]

Thanks

[@mklibuto2879]

OKAY, GET IT NOW!

[@nickmerrithew7427]

thanks

[@andersonprado1099]

Thanks a million

[@balasiusshikongo2719]

Thank you so much Sir! Your video was so helpful, but my final answer after i put 27.2/4 in a square root, i did not get 2.607..., i got 1.303840481. Maybe you can help me on how did you get that answer! I will appreciate your help.

[@obarapius1844]

good work

[@lailauthman5454]

It's very helpful, infact when I confuse in my reading (revision) I just visit this clip🙌 🌹🥀💐

[@shehrozkakakhel4946]

thank you

[@zeyadmaeed6362]

Thanks man 💓

[@nayararenteria]

So basically there is two ways to solve it depending on what it’s asking?? If it’s asking for sample you have to subtract n-1 & if it’s asking for population it’s just like 5 for example ??

[@aseelbaniissa2637]

How to send massege??

[@prateeksrivastava64]

I have a query. why sample std. deviation and population std. deviation formula are differ ? please clear me .

[@fatimkakia5419]

Please how did u get this 27,2

[@Animee2565]

Tysm

[@nazmulislam3580]

i like your classes very much

[@kwadwoamoahjohn7640]

pls can u go over it again