# Lesson Notes By Weeks and Term - Junior Secondary School 2

PICTORIAL PRESENTATION OF DATA USING PICTOGRAM, PIE CHARTS AND BAR CHARTS

SUBJECT: MATHEMATICS

CLASS:  JSS 2

DATE:

TERM: 3rd TERM

REFERENCE

• WABP ESSENTIAL MATHEMATICS FOR JSS BK 2 BY A.J.S. OLUWASANMI
• NEW GENERAL MATHEMATICS BY J.B. CHANNON & ETAL

WEEK SEVEN

TOPIC: PICTORIAL PRESENTATION OF DATA USING PICTOGRAM, PIE CHARTS AND BAR CHARTS

CONTENT:    i) The Pictogram

1. ii) The bar charts

iii) The pie charts

INTRODUCTION

A frequency table is a numerical presentation of data in an organized summary from. Diagrams, symbols and pictures sometimes catch the eye more quickly than the number. They also tell stories more easily than numbers. It is also observed that it is easier to understand frequency table than the raw data, another method of presenting data, which most graphical find easier than table, is observe method. Graphs help us to observe any patterns easily. Examples of these graphs are pictogram, bar chart, line graph and pie chart.

THE PICTOGRAM

This uses pictures to represent statistics information or data. The pictogram is also called an ideograph. A pictogram uses pictures or drawings to give a quick and easy meaning to statistical data. A pictogram is a simple way of representing data in which a number of indentical drawings or pictures and used to show the data. It is useful to use pictures which can easily be divided into halves, quarters and do on. A pictogram must have a key to show that each picture stands for. Also you need to give the diagram a title

Example: The following table shows the favorite sports of 75 students

Represent the data in the form of a pictogram.

Favouritesports            Frequency

Football                25

Wrestling                10

Boxing                    5

TableTennis                15

Swimming                20

Evaluation Question

The following table shows the number of students in JSS 1 in different houses at a certain school.

Represent the data in the form of a pictogram

 House Blue Yellow Green Purple Students 16 14 11 21

1. Essential mathematics for JSS 1 by AJS Oluwasanmi page 187
2. New general mathematics for JSS 1 by AJS Channon other. Page 125
3. MAN mathematics for JSS 1 page 211

THE BAR CHARTS

Barchart is very like a pictogram. The bars have the same width and usually have equal spaces between them. Instead of using pictures as in case of the pictogram, we must use a bar to represent the frequency of each of the item. In drawing a bar chart, we must take the following features into consideration.

1. The charts consists of bars
2. The bars must be of equal width
3. The lengths of the bars are in proportion of the frequencies being represented. The bars may be vertical or horizontal

Example

The following figures show the number of children per family in a sample of 40 households

1, 2, 4, 3, 4, 3, 8, 3, 2, 2, 3, 2, 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

1. Prepare a frequency table for this data
2. Draw a bar chart to illustrate the above data

Solution

1. Frequency table
 No of children per family 1 2 3 4 5 6 7 8 frequency 2 5 9 7 7 4 3 3

(b)

Evaluation Question

The table below shows different colours of cars found in a company’s car park. Draw a bar chart for this data.

 Colour of cars White Blue Red Grey black Frequency 20 17 10 8 15

Essential Mathematics for JSS 2 by AJS Oluwasanmi page 188

THE PIE CHART

A pie chart is a circle, which is divided into slices (i.e sectors) whose angles are used to display data.

The size of an angle of each sector gives the frequency of each value. The major advantage of a pie chart is that it enables us to see clearly how the size of parts are compared in relation to one another and to the overall total. It is important to label each sector according to the given items and also give pie chart a little.

Example: A student was given N600.00 in June as a pocket money. He spent the money as follows:

Food        =    N200.00

Transport    =    N100.00

Books        =    N120.00

Rent        =    N150.00

Miscellaneous    =    N30.00

Draw a pie chart to illustrate the data.

Solution

There are 360o in a full circle and the total amount spent was N600.00 this means N600.00 is represented by 360o; N1 is represented by 360°600 = 0.6

= 200 x 0.6

= 120o

 Items Amount Spent in Naira (N) Angle Food 200 200 x 0.6 = 120o Transport 100 100 x 0.6 = 60o Books 120 120 x 0.6 = 72o Rent 150 150 x 0.6 = 90o Miscellaneous 30 30 x 0.6 = 18o TOTAL 600 360o

120o + 60o + 72o + 90o + 18o = 360o

GENERAL EVALUATION QUESTION

400 students were asked whether they liked yam, cornflakes, bread, rice or some other type of food for breakfast, the following data was recorded.

 Type of Food Yam Cornflakes Bread Rice Other Total Frequency 65 110 80 120 25 400

Draw a bar and a pie chart to represent this information

Essential Mathematics Bk. 2 pages 303 – 307. Exercise 24.2 No 1 and page 304

WEEKEND ASSIGNMENT

1. Which of the following is not a pictorial form of presenting data?
1. Bar chart    B. Pie chart    C. Frequency distribution     D. Line graph

The pie chart below shows the course which a group of students are doing. Use the pie chart to answer questions 2 to 5

1. What is the value of angle xo?     A. 20o      B. 30o     C. 40o      D. 35o
2. Which course most students doing?      A. Engineering     B. Accounting     C. Law      D. Medicine
3. Which course has the least number of students?    A. Engineering     B. Accounting     C. Law      D. Medicine
4. What fraction of the students are doing Engineering?     A. 23      B. 14      C. 13       D. 16

THEORY

1. 40 youths who were admitted into a mental hospital due to drug abuse were asked to name the types of drugs they often take. The table shows how they replied.

Indian hemp    35%

Morphine    20%

Heroine    15%

Cocaine    30%

1. Represent this information in a pie chart
2. Find the number of youths in each category