Table, Pie chart and Graph

Frequency Distribution Table

A frequency distribution table is one way you can organize data so that it make mare sense. By counting frequencies, we can make a frequency distribution table. Here are some test scores from a math class.

80 88 91 65 74 93 82 87 70 89

99 89 70 88 78 83 59 69 87 54

94 84 96 98 46 70 90 96 88 72

89 83 74 94 80 67 77 82 92 70

The above data can be organized into frequency distribution in several ways. One method is to use intervals as a basis. The smallest value in the above data is 46 and largest is 99. The interval from 46 to 99 is broken up into smaller subinterval (called class interval) for each class interval. For each class interval, the amount of data item falling in this interval is counted. The number is called the frequency of the class interval. The results are tabulated as frequency table as follows:

Now, we can see the biggest number of the score are between 80 to 90 and the least number of scores between 40 and 50.

Pie charts

In pie-chart, the circle is divided into different sectors.It is a circular chart. Each sector represents an item in a data.

Reading pie-chart

The pie chart shows the result of a survey that was carried out to find out how student travels to school.

• What is the most common food?
  The answer is the most common method of travel in the bus as this has the largest sector on the pie chart.
  
  
• What fraction of people eats samosa?
  The answer is \(\frac{1}{3}\)
  
  
• If 8 student eat samosa, how many students go to the hotel/canteen?
  The answer is 8÷\(\frac{1}{3}\)=24

Constructing pie-charts

To construct a pie chart you need to work out the fraction of the total that the sector represents. You can then convert this to an angle and draw the sector on the chart. Look at the following example.

The table below shows the grades achieved by 30 pupils in their final exams.

To show the information in a pie chart, take the following steps:

1. Work out the total number of pupils 7 + 11 + 6 + 4 + 2=30
2. To work out the angles of each sector, work out the fraction of the total that got each grade:
   A:\(\frac{7}{30}\), B:\(\frac{11}{30}\),C:\(\frac{6}{30}\), D:\(\frac{4}{30}\) and E:\(\frac{2}{30}\)
3. There are 360° in the full turn, so to work out the angle, multiply the fraction by 360:
   Grade A:\(\frac{7}{30}\)\(\times\)360=84°
   Grade B:\(\frac{11}{30}\)\(\times\)360=132°
   Grade C:\(\frac{6}{30}\)\(\times\)360=72°
   Grade D:\(\frac{4}{30}\)\(\times\)360=48°
   Grade E:\(\frac{72}{30}\)\(\times\)360=24°
4. Construct the pie chart as given:

Graph

A line graph is most useful for displaying data or information.It is plotted as a series of points, which are then joined with the straight line.The end of line graph does not have to join to the axis.

How to make the line graph?

• Use the data from the table to choose the appropriate scale. All scales start at 0.
• Draw and label the scale on the vertical axis.
• Draw and label the horizontal axis.
• List the name of the each item.
• Locate the point on the line segment.
• Connect the points with line segments.