Pie Charts and Bar Charts

Understanding Pie Charts

A pie chart is a circular graph divided into slices to illustrate numerical proportions. Each slice represents a category's contribution to the total.

• Whole Circle: Represents the total data set, usually 360 degrees.
• Slices: Each slice's angle is proportional to the category's frequency.

How to Draw a Pie Chart

1. Calculate the Angle: Use the formula $\text{Angle} = \frac{\text{Category Frequency}}{\text{Total Frequency}} \times 360^\circ$.
2. Draw the Circle: Use a compass to draw a circle.
3. Draw the Slices: Use a protractor to measure and draw each slice based on the calculated angles.

 

Understanding Bar Charts

A bar chart uses rectangular bars to show the frequency of categories. The length or height of the bar is proportional to the category's frequency.

• Axes: The x-axis represents categories, and the y-axis represents frequency.
• Bars: Bars can be vertical or horizontal.

How to Draw a Bar Chart

1. Label the Axes: Clearly label the x-axis and y-axis.
2. Draw Bars: Each bar's height (or length) corresponds to the category's frequency.
3. Space Bars Evenly: Ensure there is equal spacing between bars.

 

Examples

Example 1: Drawing a Pie Chart

Data: A survey of students' favorite fruits: Apples (30), Bananas (20), Oranges (10).

 

Example 2: Drawing a Bar Chart

Data: Number of books read by students: 1 book (5 students), 2 books (8 students), 3 books (12 students).