Stem & Leaf diagrams

• Here are the results that 20 students achieved in a science test.

• 54 75 63 80 63 77 78 86 72 62

87 66 93 56 80 86 51 78 42 45

Task: Put these numbers in order.

Stem & leaf diagram

• 4 2 5

• 5 1 4 6

• 6 2 3 3 6

• 7 2 5 7 8 8

• 8 0 0 6 6 7

• 9 3

Key: 9 3 means ?

Stem & leaf diagram

• 4 2 5

• 5 1 4 6

• 6 2 3 3 6

• 7 2 5 7 8 8

• 8 0 0 6 6 7

• 9 3

This part is called the stem

This part is called the leaf

Key: 9 3 means 93

Stem & leaf diagram

• 4 2 5

• 5 1 4 6

• 6 2 3 3 6

• 7 2 5 7 8 8

• 8 0 0 6 6 7

• 9 3

This part is called the stem

This part is called the leaf

Key: 9 3 means 93

• Stem and leaf diagrams are useful because they give you an overall picture of your original data showing the shape of the distribution.

• We can also use them to work out the median and mode

• Draw a stem & leaf diagram to show the following data.

• The weight of 15 footballers are show as follows. (The weights are in KG)

• 67, 58, 85, 88, 77, 90, 75, 82, 85

65, 69, 70, 71, 76, 64

Stem & leaf diagram

• 5 8

• 6 4 5 7 9

• 7 0 1 5 6 7

• 8 2 5 5 8

• 9 0

• These are the times which a team of mechanics take to change the tyres at a pit stop in a Grand Prix.

8.2 7.6 5.7 6.3 4.9 6.6

7.8 6.2 5.3 7.4 5.1 6.5

Stem & leaf diagram

• 4 9

• 5 1 3 7

• 6 2 3 5 6

• 7 4 6 8

• 8 2

Key: 4 9 means 4.9

• These are the times which a team of mechanics take to change the tyres at a pit stop in a Grand Prix.

18.2 17.6 15.7 16.3 14.9 16.6

17.8 16.2 15.3 17.4 15.1 16.5

Stem & leaf diagram

• 14 9

• 15 1 3 7

• 16 2 3 5 6

• 17 4 6 8

• 18 2

Key: 14 9 means 14.9

A STEM & LEAF DIAGRAM• Below are the ages of forty motorists entered for a driving

competition, shown in a stem and leaf diagram: 0 5

1 9

2 8 8 6 9 2 6 9

3 8 4 5 8 7 9 5 7 7 8 6 3 5 2 6 9 3

4 4 1 6 5 5

5 2 5 9

6 6 1 3 2 0

7

8 1 Represents 81 years (this is the scale)

BACK-TO-BACK STEM & LEAF DIAGRAM

• Here are the weights of students from two different tutor groups

9 5 1 7

2 6 0 2 3 5 8

5 3 0 7 1 2 5 6 6 7

9 7 5 1 1 8 3 5

8 6 2 1 9 2

Coursework – Word lengthsWord Length Frequency

0 6 6 6 6 6 6 6 6

4 0

0

1

11

1

7 7 7 7 7

8 8 8 8

9 9

0 0 0

1 1

2 2

3

86

7 5

8

0

9 2

10 3

11 2

12 2

13 1

0 6 6 6 6 6 6 6 6

0

0

1

11

1

7 7 7 7 7

8 8 8 8

9 9

0 0 0

1 1

2 2

3

0

Coursework – Word lengths

What is the median?

What is the mode?