Join TSR now and get all your revision questions answeredSign up now

S1 edexcel standard deviation formula? Watch

    • Thread Starter
    Offline

    0
    ReputationRep:
    On page 60 of heinemann edexcel S1 there is a formula for the best estimate of the standard deviation of a sample......

    (1/(n - 1))(sum (x^2) - ((sum (x))^2)/n)

    and they have practice questions on this. I've looked through past papers and i've never seen this formula used for finding standard deviation estimates of 'samples'.

    I'm kind of confused as to when I should be using this formula, if at all. Is there a possibility it will be required in the exam?
    Offline

    1
    ReputationRep:
    Ignore it - you don't need to know this formula for Edexcel S1
    • PS Helper
    Offline

    2
    That's an S2 formula for finding an unbiased estimator for the standard deviation; you won't need it in S1.
    Offline

    0
    ReputationRep:
    I've done S1 twice already (and today for the third time lol) and we're told to do 'the mean of the squares minus the square of the mean'.
    That is ?((x^2)/n)-(?(x/n))^2
    Or at least it's something like that
 
 
 
Poll
Is GoT overrated?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.