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]

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[@RadfordMathematics]

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

[@bryanalozie8917]

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[@RadfordMathematics]

Thanks for the kind comment!
Really glad it helped 😊

[@redcapshorts9232]

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[@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 ✌️

[@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!!!

[@tarokicat]

Thank u so much this helped alot

[@highmanga535]

Thank you. Good lesson!!!

[@RadfordMathematics]

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

[@noor-oj9he]

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[@RadfordMathematics]

Truly glad it helped!
Take good care 😊

[@lordvolandemort4750]

thank you so much

[@RadfordMathematics]

Really glad it helped 😊

[@haze4612]

thank you so much!

[@RadfordMathematics]

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

[@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

[@xanwess]

thank you

[@RadfordMathematics]

Thanks for your comment Wes! Really glad it helped 😊

[@NoReplyForIdiots]

Just subbed

[@RadfordMathematics]

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

[@user-zu4go5tz6c]

this helped me very much thank u for this effort

[@RadfordMathematics]

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

[@mohamedhossam193]

Thank you sir

[@mohanthrishan9708]

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

[@RadfordMathematics]

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

[@vaibhavmn]

have math tom really saved me

[@RadfordMathematics]

Really glad it helped 😊

[@user-zu4go5tz6c]

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[@RadfordMathematics]

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

[@guiguimvz]

valeu estamos juntos❤👍

[@khalifaalfa4826]

thanks allot

[@RadfordMathematics]

Thanks for your comment Khalifa!
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

[@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 😊

[@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!

[@israeltenny5042]

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

[@RadfordMathematics]

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

[@anasnaufal3101]

Why you dont used upper boudary

[@blessinglowo2915]

thank you

[@edgypatch]

Thanks sir

[@RadfordMathematics]

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

[@edgypatch]

@@RadfordMathematics yes sir