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# Statistics - Histogram watch

1. When working out the frequency density to draw your histogram, what do you do when the class is just one number such as '8' instead of '1-3' where your class interval would be 2??
hope someone can help, thanks!!
2. (Original post by kjm98)
When working out the frequency density to draw your histogram, what do you do when the class is just one number such as '8' instead of '1-3' where your class interval would be 2??
hope someone can help, thanks!!
You made a wrong assumption in both of those examples, when a class is a single values such as "8" (lets suppose this is length we are talking about, in this case mm) then anything that is 7.5mm long up to 8.49999999...mm (which tends to 8.5mm) will round to 8mm. As a result your class width is 8.49999999... - 7.5 = 1mm, that is your class width for the "8" value.

Now if the group is "1-3" then the minimum value that will fit in that group is 0.5 and the highest is 3.49 recurring, 3.4999... - 0.5 = 3 so the first class width would be 3, not 2
3. (Original post by Ronnie S)
You made a wrong assumption in both of those examples, when a class is a single values such as "8" (lets suppose this is length we are talking about, in this case mm) then anything that is 7.5mm long up to 8.49999999...mm (which tends to 8.5mm) will round to 8mm. As a result your class width is 8.49999999... - 7.5 = 1mm, that is your class width for the "8" value.

Now if the group is "1-3" then the minimum value that will fit in that group is 0.5 and the highest is 3.49 recurring, 3.4999... - 0.5 = 3 so the first class width would be 3, not 2
Thank you so much!! Really helped!

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