Creating and Understanding Pie Charts

What is a Pie Chart? A pie chart is a circular chart (pie-shaped); it is split into segments to show percentages or the relative contributions of categories of data.

How do I draw a pie chart? Step Decide on the total number of categories. In other words, identify the categories that you will use Collect the data so the number per category can be counted (Frequency Table) Brand Name TallyFrequency Daz |||| |||| |||| |||| |||| |||| |||| |||| 40 Ariel |||| |||| |||| |||| |||| |||| |||| |||| |||| |||| |||| |||| 60 Bold |||| |||| |||| |||| |||| 50 Fairy |||| |||| |||| |||| |||| 30 Other |||| |||| |||| |||| 20 TOTAL200

How do I draw a pie chart? Step 2 Brand Name Units sold / year in 10 6 Degree Share Daz40 x 360 = 72 o x 360 = 72 o Ariel60 x 360 = 108 o x 360 = 108 o Bold50 x 360 = 90 o x 360 = 90 o Fairy30 x 360 = 54 o x 360 = 54 o Other20 x 360 = 36 o x 360 = 36 o Total200 Total = 360 o Total = 360 o To calculate degree share, you need to divide the share that the category has by the total units and then multiply by 360 (there are 360 degrees (°) in a circle)

How do I draw a pie chart? Step 3 – Drawing the chart 1 st Draw a Circle With a protractor measure 72 o Mark this angle and draw a line from the centre to the mark Turn the protractor so that the zero is now on this line Now measure 108 o Now measure 90 o And finally 54 o You should now be left with 36 o Again, turn the protractor so that zero is now on this line Again, turn the protractor Lightly, draw a vertical line through the centre Please note that due to the limitations of the software some measurements on this screen are not totally accurate.

How do I draw a pie chart? Step4 It may be necessary to work out the percentage and include this in the labelling. How would we do this? Brand Name Units sold / year in 10 6 % age Daz40 (40 ÷ 200) x 100 = 20% Ariel60 (60 ÷ 200) x 100 = 30% Bold50 (50 ÷ 200) x 100 = 25% Fairy30 (30 ÷ 200) x 100 = 15% Other20 (20 ÷ 200) x 100 = 10% Total200 To calculate degree share, you need to divide the share that the category has by the total units and then multiply by 100 (the whole circle is equal to 100%).

Exercises Use a pie chart to illustrate the data given below, fully label the chart and show the percentage value of each sector. 180 FE college students were asked what they intended to do next year. 54 Going to university 40 Staying at college 62 Going into employment 24 No firm intention

Exercises At a concert, the ages of 115 people were recorded as: Under and over 24 Draw a pie chart using this data, give the data labels values in % ages

Thirty people were surveyed in a shopping centre and asked their ages. These are displayed below a)Draw a tally-frequency table. b)Using the data in your frequency table, construct a table to calculate the angles in a pie chart. c)draw and fully labelled a pie chart to show the percentage values.