Linear Interpolation Recap - Edexcel Maths A Level, Statistics

A recap of using linear interpolation to estimate quartiles in grouped data, from the Year 1 syllabus in the Edexcel A level maths course.

Pause and try it yourself. Check if you get the correct result.

[joyfulgore]

So much simpler than the method i was taught, thanks

[umarworks]

helpful, have my stats exam in 1hr. never able to do this now i can!

[NihouNi]

This is now in Edexcel's GCSE Statistics. Thanks for all your clarification.

[andrewwhite]

I would like to compliment the clarity of your explanation. I was not going to add a comment and then I read how helpful your replies to people that remained confused were and wanted to commend you.

[flupyclouds]

Thank you so much, I will sacrifice my first born child for you 10 years later because of how helpful this was.

[osgarnh]

Do you not have to add 1 to the total frequency before dividing to get the quartiles or is either accepted.
eg. (50+1)/4 rather than 50/4

[evapostormz]

Hiya, real quick question in terms of rounding. The question only wants the final answer to be rounded so would rounding early give you an incorrect answer? Q1 is 63.95833 and Q3 is 75.3125, finding the IQR of this would be (75.3125-63.95833 = 11.354…). This answer would round up to 11.4 instead of the 11.3 in your answer. Would both answers get full credit? Thanks in advance 🙏

[jillian]

Could you explain why when we’re finding Q1 we don’t start the interpolation with the value 4 as the lower class boundary, but instead we use 3? As I thought 3 wasn’t a part of the class we’re looking at and would instead belong to the first class? Thank you in advance.

[stormdog]

this was really helpful as a recap for the topic, but surely for the lower boundary for q1 it should be 59.5 because the question its greater than or equal? or am i getting that confused with another topic

[tombarbe-firth-nncz]

Why do we put the 50 over 4 to begin with? How do we get that 50?

[maxhesp]

Thx for the video, helpted me allot LFG

[xqhzkqm]

why’s this gonna be in my year 10 exams (it’s february) and it says a level

[Myiiii]

hi, really helpful explabation but where did 64 come from at the end?