Graphs

A graph is a pictorial representation of statistical data clearly. Graphs are often more helpful than list or tables. For this stage, Graphs include:

1. Pictogram
2. Bar Chart
3. Pie chart

Pictogram

In a pictogram, pictures represent the frequency of data values.

Example:

Study the frequency below and represent the information in a pictogram.

Bar Chart

In a bar chart, the height (or length) of a bar represents the frequency of the data values.

Examples:

Study the frequency below and represent the information in a bar chart.

Pie Chart

In a pie chart, a circle represents all the data, and the sizes of its sectors are proportional to each item.

Examples:

A farmer has 120 animals as shown in the pie chart below:

(a) Using a protractor, measure the angles representing each animal.

(b) Find the number of (i) cows (ii) goats (iii) sheep

Solution:

(a) Cows = 180^o

Goats = 120^o

Sheep = 60^o

(b) Number of cows = 180360×120 = 60 cows

Number of goats = 120360×120 = 40 goats

Number of cows = 60360×120 = 20 sheep

CLASS ACTIVITY

1. From the list of scores given below, create a (i) rank ordered list. (ii) frequency table.

29, 75, 36, 70, 37, 66, 39, 64, 47, 63, 47, 47, 58, 52, 54

2. Represent the information below in a (i) pictogram. (ii) bar chart.

ASSIGNMENT

3. The instruments played by 240 members of a school choir is represented in the pie chart below.

(a) How many choristers played the violin?

(b) What percentage of the choristers plays the saxophone?

(c) What fraction of the students plays the keyboard?

(d) Which instrument is played by the least number of choristers?

(e) How many are they?

(f) If more instrumentalists are to be trained, what do you think they will be selected to play?

PRACTICE QUESTIONS

1. From the list of scores given below, create a (i) rank ordered list. (ii) frequency table.

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

2. Represent the information below in a (i) pictogram. (ii) bar chart.