2. Pie chart – Used for data that can be counted, used to compare individual ‘bits’ of data with the whole. – The whole circle represents all the data. – Each sector represents one ‘bit’ of information.

3. FlavourNumber (n) Strawberry16 Orange5 Peach9 Blackberry4 Other11 Pie chart This shows the flavours of yoghurt preferred by 45 students You are required to draw a Pie Chart to present this information. You will need to extend the table to be able to calculate the angles.

4. 11Other 4Blackberry 9Peach 5Orange 16Strawberry Number (n) Flavour Totals n Total n Angle Rounded Angle The angles are calculated by multiplying the respective numbers in column 3 by 360 o This last column is only required IF the angles in the previous column are not whole numbers

5. 88 o 0.2444411Other 32 o 0.088894Blackberry 72 o 0.29Peach 40 o 0.111115Orange 128 o 0.3555616Strawberry Col 3 x 360Number (n)Flavour n Total n 360 o 1.000045Totals It is important to check that the totals of the last two columns add up to 1.0000 and 360 o, as this ensures that any errors can be recognised and dealt with. Another important thing to remember is that IF you have decimal angles and you round them, DO SO CAREFULLY and recheck that the rounded angle add up to 360. You may need to adjust!!!

6. Make sure you measure ALL the angles carefully, DO NOT assume the last angle to be correct… MEASURE IT !!!! A key is important OR you can label the individual sectors with the NAMES of the “bits”.

7. Now you try some questions BIG textbook p 413 – 414 Questions 2, 3, 4 and 6 p 415 – 416 Questions 1, 3, 5, 7

8. Interpreting Pie Charts Sometimes you may be given a completed pie chart and asked to interpret the information. The pie chart on the left shows the heights (in cm) of 30 pupils in a class. Which group contains the most people? 151-160cm

9. How many people are in the group 121-130cm? 3 If you had a problem, remember that 36° is one-tenth of 360°, so one-tenth of the people are in this group. You may need to measure the angles with a protractor first!!!