Pie Charts

Why a Pie Chart? □Very visual □Easy to read □Slices show clearly how the data is distributed

Data for a Pie Chart □Usually given in a table format □This data was obtained from a class survey on “Favourite Drinks” Favourite Drink Frequency Milk7 Orange9 Cola13 Water6 Tea2 Other3 These are the answers given Other allows for “unexpected” answers How many people said they preferred this drink

1 Work out the slices Favourite Drink Frequency Milk7 Orange9 Cola13 Water6 Tea2 Other3 Total 40 We need to calculate the size of each slice in the pie chart 40 people responded to the survey If very person had their own slice, each would get the same of the circle X 360º= 9º

If 1 person is 9º Angle Total 360º Favourite Drink Frequency Milk7 Orange9 Cola13 Water6 Tea2 Other3 9 x 9 13 x 9 6 x 9 2 x 9 3 x 9 7 x 9= 63º = 81º = 117º = 54º = 18º = 27º

2 Draw the Pie Chart Mark a centre for the Pie Chart x Draw a circle with centre on the markUse compassesOr draw around an Angle Measure x

2 Draw the Pie Chart Draw line vertically from centre to circumference Draw LARGEST slice first i.e. Cola = 117º Cola Label the slice ‘Cola’ Do not enter the angle or the frequency! x

2 Draw the Pie Chart Draw NEXT LARGEST slice i.e. Orange = 81º Turn Protractor so that 0º marker is at the end of line just drawn Orange Cola

2 Draw the Pie Chart Then Milk = 63º Orange Cola Milk

2 Draw the Pie Chart Then Water = 54º Orange Cola Milk Water

2 Draw the Pie Chart Then Other = 27º Orange Cola Milk Water Other

2 Draw the Pie Chart The LAST slice is already drawn – just check it Tea = 18º Orange Cola Milk Water Other Tea Remove the small guide marks carefully Give the Pie Chart its Title Class 7A’s Favourite Drink