Turn on thread page Beta
 You are Here: Home >< Maths

# S2 edexcel continuity correction watch

1. Hi everyone, I have just started the normal approximations topic for S2 edexcel maths and for some reason on each different resource I have (I use exam solutions, my text book and other online notes etc) each is telling me different things about continuity correction. I am unsure whether or not to add 0.5 or subtract it when you have different probabilities which include bigger(or smaller) and equal to/ bigger (or smaller) than X. And whether or not to use <_ when you change it to a continuous or if it must be just < as in continuous PROBABILITY =X is 0. I hope this makes sense x I would really appreciate if someone could clear up what I am confused about xx thanks so much

(If perhaps someone could just tell me the rules that may be the easiest way, )
Posted on the TSR App. Download from Apple or Google Play
2. (Original post by biohalle)
Hi everyone, I have just started the normal approximations topic for S2 edexcel maths and for some reason on each different resource I have (I use exam solutions, my text book and other online notes etc) each is telling me different things about continuity correction. I am unsure whether or not to add 0.5 or subtract it when you have different probabilities which include bigger(or smaller) and equal to/ bigger (or smaller) than X. And whether or not to use <_ when you change it to a continuous or if it must be just < as in continuous PROBABILITY =X is 0. I hope this makes sense x I would really appreciate if someone could clear up what I am confused about xx thanks so much

(If perhaps someone could just tell me the rules that may be the easiest way, )
You are, in essence, replacing a point value with an interval.

E.g X=4, is replaced with X in the interval [4-0.5, 4+0.5] = [3.5,4.5]

So, with a strict inequality, X>4, now becomes X > everything in the interval (or less), i.e. X>4.5

Similarly X<4 becomes X<3.5

With a weak inequality X>=4, this includes the possibility that X=4, so we include the interval and this becomes X>=3.5

Similarly X<=4, becomes X<=4.5.

Whether you use X<=4.5 or X<4.5 doesn't matter for a continuous distribution. I'd go with what the original inequality was, strict or weak.

Turn on thread page Beta

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 14, 2018
Today on TSR

### Unofficial Markscheme list 2018

Find all the answers here

### 2,991

students online now

Exam discussions

Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

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