Cumulative Frequency Diagram, Median, Lower & Upper Quartile, Interquartile Range, Percentile

We learn how to draw and use a cumulative frequency diagram to find the median, lower and upper quartiles, the interquartile range, 90th percentile and how to use the diagram to draw a box plot.
******* TIME STAMPS / CHAPTERS *******
00:00 Introduction
00:50 Cumulative Frequency Column
02:13 Plotting Points & Curve for Cumulative Frequency Diagram
04:33 Median Value
05:55 Lower & Upper Quartile
07:37 Interquartile Range
08:02 Median at n/2 or (n+1)/2 ?
09:03 Box Plot
10:22 90th Percentile (How to Find it)
11:54 Percentage Measuring Less than 32cm

[@kelxey.5989]

thank you so much for the useful info! You’ve taught me more than my math teacher did in 13 minutes instead of an hour:))

[@RadfordMathematics]

Thanks for your kind comment Kelxey, I really appreciate it 😊.
Truly glad to read / hear this video helped!!!
Take good care ✌️
John Radford.

[@elly1976]

I have watched more than 20 videos related to this topic. Your tutorial is so easy to understand and very clearly explained. Thank you so much!

[@RadfordMathematics]

Thanks for such a kind comment!!
I’m really glad this tutorial helped 😊

[@zebuluncooper607]

my math test is coming up soon, made my doubts disappear in a millisecond just like that! you are truly amazing will definitely show this to the rest of my class who is struggling with cumulative frequency as well.

[@RadfordMathematics]

Hadn’t seen this comment 😊
Thank you so much for such kind words Zebulum! Truly glad you (and maybe your classmates) found it helpful 😊

[@ezramusonda6572]

I need more different lessons taught by Mr Radford also on how to plot a histogram

[@mogumoguokayu1418]

Thank you, good sir, you are the only channel on youtube that has any quality content. I'm sitting for my exam in 15 minutes and your videos are really coming in clutch no cap.

[@RadfordMathematics]

Thanks for your kind comment!!
I’m truly glad this videos (and others) helped 😊.
Hope the exam(s) went well 🤞

[@redcapshorts9232]

Saved my life. I needed this for maths homework

[@bryanalozie8917]

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[@RadfordMathematics]

Thanks for the kind comment!
Really glad it helped 😊

[@marijajohn4471]

Very informative and understanding keep it up

[@RadfordMathematics]

Thanks for you kind comment!
I’m really glad it helps 😊

[@leeharuchiyo351]

my p4 is in 8 hours and this is the one topic ive never gotten the hang of, but you explained it really well! thanks sir!

[@RadfordMathematics]

Thanks for your comment! I’m really glad it helped 😊

[@sifjdfijdnfepijfwifwjiwfij4208]

Thank you- this was super helpful!

[@RadfordMathematics]

Thanks for your comment, I really appreciate it!
Truly glad it helped 😊.
Take Good Care ✌️

[@tarokicat]

Thank u so much this helped alot

[@insanityb3ast258]

good day , this vid was VERY helpful i have a test tomrrrow so this was great revision

[@RadfordMathematics]

Thanks for your comment! I’m really glad it helped 😊.
All the best for tomorrow’s test!!!

[@noor-oj9he]

Thank you so much that was so helpful 😭💗💗

[@RadfordMathematics]

Truly glad it helped!
Take good care 😊

[@highmanga535]

Thank you. Good lesson!!!

[@RadfordMathematics]

Thanks for your feedback, I really appreciate it !!
Truly glad it helped 😊

[@user-zu4go5tz6c]

this helped me very much thank u for this effort

[@RadfordMathematics]

Thanks for your comment!
I’m really glad it helped 😊

[@tibatsondube405]

gor an exam in less than 24hrs wow thank you soo much evrything is well explained

[@RadfordMathematics]

Thanks for the comment!
I’m really glad it helped 😊

[@blessinglowo2915]

thank you

[@lordvolandemort4750]

thank you so much

[@RadfordMathematics]

Really glad it helped 😊

[@mohamedhossam193]

Thank you sir

[@haze4612]

thank you so much!

[@RadfordMathematics]

Thanks for your comment 😊
I’m truly glad it helped!!
Take good care ✌️

[@Crabby.1]

Just subbed

[@RadfordMathematics]

Thanks Bred 😊
Truly hope this video helped!!
Take good care 🌱

[@vaibhavmn]

have math tom really saved me

[@RadfordMathematics]

Really glad it helped 😊

[@mohanthrishan9708]

Thank you sir I have my math's exams tomorrow :)

[@RadfordMathematics]

Truly glad it helped 😊
Good luck tomorrow!!! 🤞

[@natesanjyothikumari5256]

Very well explained sir,

[@RadfordMathematics]

Thanks Natesan! I’m really glad it helped 😊

[@natesanjyothikumari5256]

@@RadfordMathematics i learned so much sir from this video, your explanation is clear and everyone can understand easily, please do more videos sir, you are very good teacher,

[@natesanjyothikumari5256]

Lots of love from india sir

[@guiguimvz]

valeu estamos juntos❤👍

[@khalifaalfa4826]

thanks allot

[@RadfordMathematics]

Thanks for your comment Khalifa!
I’m truly glad this video helped 😊
Take good care ✌️

[@user-zu4go5tz6c]

alhamdulilha I got good Marks because of your video may Allah succeed u and convert u to the right path of islam inshalla u will succeed ☺

[@RadfordMathematics]

Thanks for your comment!
I’m truly glad this video helped 😊
Take good care!

[@danielagyei3931]

So is easy like that waow

[@Nei88]

When do you need to calculate the class width

[@israeltenny5042]

You just saved my education carrier..thank you Sir🙏🏾

[@RadfordMathematics]

Really glad it helped 😊
Good luck for the rest of your course!

[@AbdurRaheem_56_16-nc5yl]

Sir does it matter if we +1 in estimating median?

[@RadfordMathematics]

No it doesn’t matter but usually, in exam questions, the total frequency is a multiple of 4 (like 80, 200, …) so it’s in our best interest to use n/2 instead of (n+1)/2.
Furthermore, since when we work with a cumulative frequency diagram, we’re estimating: there’s no gain in accuracy when we use (n+1)/2 😊.
Really hope that helps.
All the best!

[@user-uk6lz3sq9t]

Is it wrong when I be using n+1/2 instead of n/2

[@RadfordMathematics]

No it’s technically not wrong.
But when it comes to cumulative frequency diagrams we usually just take n/2 (you’ll usually end up with a more convenient number as well)
Like 80/2 is 40 (easy to read off the graph) rather than (80+1)/2 = 40.5 (not convenient).
Since we’re working with grouped data, where each row of the table corresponds to a class interval we’re not losing in accuracy… . The key thing to remember is that when we use a cumulative frequency diagram: we are estimating. So may as well use n/2 , which is far more convenient.
Hope that makes sense 😊

[@anasnaufal3101]

Why you dont used upper boudary

[@xanwess]

thank you

[@RadfordMathematics]

Thanks for your comment Wes! Really glad it helped 😊

[@edgypatch]

Thanks sir

[@RadfordMathematics]

Thanks for your comment 😊
I’m really glad that video helped!!
Take good care ✌️

[@edgypatch]

@@RadfordMathematics yes sir