Drawing Stem and Leaf Diagrams Teach GCSE Maths Petrol Consumption (mpg) Key: 5 7 means 57 mpg

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e.g.1The table gives the 10 “best” petrol consumption figures (mpg) for cars in Draw a stem and leaf diagram to display the data. 1.Decide on the size of numbers in the stem: A spread from 57 to 83 suggests a stem in tens, from 5 tens to 8 tens. Petrol Consumption (mpg) Key: 5 7 means 57 mpg 3 2.Check the numbers are in order before writing the leaves. Start with the smallest Give a title and key. Crown Copyright Source: Vehicle Certification Agency (VCA)

e.g.2.The table gives the body mass index (BMI) of 18 army recruits. (a) Draw a stem and leaf diagram to show the data. (b) Find the median. 25·425·726·026·826·927·1 27·6 27·728·128·228·7 28·828·929·329·629·831·1 BMI is given by weight (kg) / (height (m)) 2 e.g. weight = 74 kg, height = 1·69 m BMI = 74 ÷ (1·69) 2 = 25·9 In 2006, the maximum for army recruits was increased from 28 to 32. Tell your partner what numbers you would choose for the stem. Ans: The best choice is 25, 26, The leaves will show the tenths.

25·425·726·026·826·927·1 27·6 27·728·128·228·7 28·828·929·329·629·831·1 Solution: Key: 25 4 means 25·4 Body Mass Index of 18 army recruits (a) e.g.2.The table gives the body mass index (BMI) of 18 army recruits. (a) Draw a stem and leaf diagram to show the data. (b) Find the median.

Key: 25 4 means 25·4 Body Mass Index of 18 army recruits Solution: The total frequency is even so we need the mean of the 2 middle values: (b) Find the median. Median is ½ (27·7 + 28·1) = 27·9 Tell your partner which values we need. We need the mean of the 9 th and 10 th... 27·7 and 28·1

SUMMARY 1.Decide on the size of numbers in the stem. 2.Check the numbers are in order before writing the leaves. Start with the smallest and work away from the stem. 3.Give a title and key.

Exercise 1. Stem and leaf diagrams are to be drawn for the following data set which gives the ages of 27 people in a restaurant (a) Write down sensible numbers to use in the stem. (b) State the size of the numbers in the leaves. Answer: For example, (a) 4, 5, 6, 7 (b) Units (c) Draw the diagram. If you had a different answer to (a), use your numbers and decide if they work well.

Exercise Key: 4 2 represents Ages of 27 people in a Restaurant (c) Answer

Exercise 2. Stem and leaf diagrams are to be drawn for the following data set which gives the temperatures of 18 towns (  C ) on 21 st February ·27·27·57·57·77·78·38·38·78·78·78·78·78·78·98·99·09·0 9·39·39·79·710·110·610·9 11·111·411·6 (a) Write down sensible numbers to use in the stem. (b) State the size of the numbers in the leaves. Answer: (a) For example, 7, 8, 9, 10, 11 (b) Tenths Now draw the diagram. If you had a different answer to (a), use your numbers and decide if they work well. Adapted from Crown copyright data supplied by the Met Office.

Exercise 7·27·27·57·57·77·78·38·38·48·48·48·48·58·58·88·89·09·0 9·39·39·79·710·110·610·9 11·111·411· February temperatures ( 18 towns ) (c) Answer Key: 7 2 represents 7·2  C 9961