Chapter 3: NORMAL DATA SETS
(Also known as  BELL SHAPED data sets)


Normal data sets are Symmetrical in shape and follow the 68-95-99.7% rule

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The 68-95-99.7% rule says:  In a normal data set: 

• about 68% of all the data lies within one standard deviation of the mean
  
• about 95% of the data lies within two standard deviations of the mean
  
• about 99.7% of the data lies within three standard deviations of the mean
  

THEORY SHEET
Download a Word document containing all the diagrams shown on this page relating to the BELL shaped DATA SET for  your THEORY book. 

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bell_shaped_data_set_and_68-95-99.7_rule.docx
File Size:	84 kb
File Type:	docx

Download File

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Here are two videos (Part One and Part Two) which clearly explain the 68-95-99.7% Rule

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                                                         Here is a video which explains z scores really well.

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TEST YOURSELF!  Try these two questions from the 2013 Further Maths Exam 1. Click on the button at the bottom to check your answers.

Click here to check your answers!