A **Stem-and-Leaf Diagram** is a way of organising a list of numerical data. The stem consists of the first part of the number. The leaves consist of the last digit of the number. The diagram always has a **Key**, which normally uses the first entry in the table and describes what the entry means.

Creating a Stem-and-Leaf diagram is a two-stage process - the first step is to create an unsorted list where the data is allocated to stems; with the second step used to place all the leaves in order.

The results of a Maths test are as follows:

51, 45, 62, 67, 63, 47, 48, 59, 68, 57, 52, 54, 65, 67, 66, 47, 56, 57, 49, 58, 57, 66

Create a Stem-and-Leaf diagram to show this information.

First organise the data by the first character. This will give you an unsorted list.

Then sort the list, organising the list by first character and, on each row, putting the second characters in order.

You will lose a mark if you do not provide a key.

Answer: Unsorted Stem-and-Leaf diagram:

5 | 1 | 9 | 7 | 2 | 4 | 6 | 7 | 8 | 7 |

4 | 5 | 7 | 8 | 9 | |||||

6 | 2 | 7 | 3 | 8 | 5 | 7 | 6 | 6 |

Sorted Stem-and-Leaf diagram:

4 | 5 | 7 | 7 | 8 | 9 | ||||

5 | 1 | 2 | 4 | 6 | 7 | 7 | 7 | 8 | 9 |

6 | 2 | 3 | 5 | 6 | 6 | 7 | 7 | 8 |

Key 4 | 5 | = 45 marks |

From the Stem-and-Leaf diagram, above, what is the range of marks from the maths test?

First entry is 45; last entry is 68

68 - 45 = 23

Answer: 23

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