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Form 3 Geography: Statistical Methods online lessons

How to construct proportional divided circles.

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Proportional divided circles.
-This is a case where two or more divided circles are drawn with each circle representing a separate set of statistical data.
-Sets may have different total quantities or values.
-Proportionately drawn circles are then subdivided just like the simple pie-charts
-The table below shows causes of death in countries X,Y and Z in the year 2003.

Steps :
i)Find the square roots of the totals for each set of data.
ii)Using the figures obtained in (i) , find a suitable scale for the radii of the circles
taking care that the circles do not become too large or too small
iii) For each set of data, calculate the percentages and angles as in simple pie-charts.
iv) Drawn the circles using the scale in (ii) and insert the details just like in simple pie-charts labelling each component .
-Shade same components in the same way/color.
v) Give the circles a title, and if necessary a key.
Working:
-Calculate the square roots of each of the totals so as to determine the radius of each circles.
Scale: 1cm rep. 20 units.
- Radius of circle for country X= 6 cm
- Radius of circle for country Y= 4.5cm
- Radius of circle for country Z= 1.5 cm

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