# Statistics

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:

1. Collecting data: to distinct ways of collection data are by carrying out experiments and by survey.
2. sorting and tabulating data
3. presenting data visually by means of diagrams
4. interpreting result
Types of Presentation
5. list and table
6. 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
7. Pictogram: uses picture or drawing to give a quick and easy meaning to statistical data.
8. Bar chart: is very like pictogram. Data are represented by a bar instead of a picture. The height represent the frequency of each value.
9. 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