A-Level Maths: L3-06 [Data: Estimating the Quartiles from Grouped Data]

[ezclapz]

Hi sir quick question, I cant seem to understand why sometimes the number are rounded to .5 and sometimes they are kept as whole numbers. When should we round to .5 and when should we keep it as a whole number thats what im confused about can you kindly answer, and great video by the way.

[gslayer]

For the third example, the lower quartile is more towards the 4<x<8 section than the 7<x<22 section, so why use the second one?? The middle of 3 & 20 is 11.5, and 10 is below that…. Surely the lower quartile would be 6.24 to 3sf??? Can you explain please

[yillokimo]

great video, just one question, is the reason why boundaries weren't used for the second example because age is discrete data?

[tellesthegoat]

when doing interpolation is there a small range of answers? because i use a different method and my answers are close to yours but not similar

[imthiyazrahman]

I’ve got a dumb question 🙋‍♂️, I understand age, you have round to the according age however, why use 21 and not like 20.99 or something idk I think that thing is hurting my brain

And technically if it’s 20.99 they’re still 20 right so shouldn’t it just be 20?
And the next bit why isn’t the UQ 30? If it’s in that bracket?

[wilhelmvongreim]

Hello sir, what if I did not get a whole number whilst dividing the total frequency? Should I do interpolation according to the number I got?

[khaled-ighz]

HI SIR

I have a question regarding the bounds so the number you put on the top of the number lines correct me if I'm wrong but is this always the case:

1. if the class has the line between numbers e.g. 12-13 then lower bound = 11.5 and upper = 13.5 ( so ones with the line between class numbers always have the 0.5 decimal )
2. for age e.g. 10-15 lower bound = 10 upper= 16 ( so lower bound always same but upper go up by 1 )
3 and for a class containing either > and < or the greater than or equal to or less than or equal to symbol e.g the last example in the vid the lower and upper bound stay same so no change to values e.g. not like first one where it is 0.5 more or less?

thanks for your help hope to hear from you soon :)))

[joshuacarpenter]

I saw something about inter percentile range in my textbook?