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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
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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. 

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.

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!