Statistics is the branch of mathematics which deals with the study of data. Data mean information which are usually given in the form of numbers or facts. The information is called Statistical data or Statistics. Statistics involves:

- Collecting data: to distinct ways of collection data are by carrying out experiments and by survey.
- sorting and tabulating data
- presenting data visually by means of diagrams
- interpreting result

Types of Presentation - list and table
- graphs

(a) Lists and tables

Rank order: means in order from highest to lowest

Frequency table: means the number of times something happens.

Tally: tally chart are usually grouped in fives. Four tallies are drawn vertically with the fifth one drawn across them 1111

(b) Graphical presentation - Pictogram: uses picture or drawing to give a quick and easy meaning to statistical data.
- Bar chart: is very like pictogram. Data are represented by a bar instead of a picture. The height represent the frequency of each value.
- Pie chart: A pie chart is a graph in the shape of a circular pie.

Examples

(1) The following raw data shows the number of vehicle owned by 25 business men in Lagos. 2, 5, 3, 4, 6, 3, 4, 7, 5, 4, 7, 7, 8, 9, 5, 3, 4, 5, 7, 4, 4, 8, 2, 2, 5.

(a) Arrange the data in increasing order

(b) Arrange the data in decreasing order

(c) How many men own 3 vehicles, 4 vehicles, 9 vehicles and less than 5 vehicles each?

Solution

(a) Increasing order: 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 7, 7, 7, 7, 8, 8, 9.

(b) Creasing order: De9, 8, 8, 7, 7, 7, 7, 6, 5, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 3, 3, 3, 2, 2, 2.

(c) 3 men own 3 vehicles, 6 men own 4 vehicles, 1 man own 9 vehicles and 12 men own less than 5 vehicles each.

(2) The following figures show the number of children per family in a sample of 40 households. 1, 2, 4, 3, 5, 3, 8, 3, 2, 2, 3, 4, 5, 6, 5, 4, 2, 1, 3, 2, 4, 5, 3, 8, 7, 6, 5, 4, 5, 7, 6, 3, 8, 6, 3, 5, 7, 5, 4, 3.

(a) Use a tally mark to prepare a frequency table for this data

(b) What is the highest frequency of numbers of children per family?

Solution

(a) Frequency table

No of children per family Tally Frequency

1 ll 2

2 llll

5

3 llll llll

9

4 llll l

6

5 llll lll

8

6 llll 4

7 lll 3

8 lll 3

Total 40

(b) 9 households has 3 children each. The highest frequency of number of children per family is 3.

(3) A student was given ₦600 in June as a pocket money. He spent the money as follows

Food = ₦200

Transport = ₦100

Books = ₦120

Rent = ₦150

Miscellaneous = ₦30

Draw a pie chart and bar chart to illustrate the data

Solution

There are 3600 in a full circle and the total amount spent was ₦600

₦1 represent by 3600

600 = 0.60 or multiply the fraction by 3600

Items Amount spent in ₦ Angle

Method 1 Angle

Method 2

Food 200 200 x 0.6 = 1200 200/600 x 3600 = 1200

Transport 100 100 x 0.6 = 600 100/600 x 3600 = 600

Books 120 120 x 0.6 = 720 120/600 x 3600 = 720

Rent 150 150 x 0.6 = 900 150/600 x 3600 = 900

Miscellaneous 30 30 x 0.6 = 180 30/600 x 3600 = 180

Total 600 3600 3600

Assignment

Ex 18b question 1 and 3

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