Representation of data using pie-charts is explained in this page.

*click on the content to continue..*

Consider the number of pens a student carries in a group of `20` students. The raw data is given as :

`2`, `1`, `2`, `4`, `2`

`3`, `2`, `2`, `2`, `3`

`3`, `2`, `2`, `3`, `2`

`2`, `2`, `4`, `2`, `2`

The figure provides the tally and tabular representation of the given raw data.

Considering the number of pens a student carries. The figure provides the bar graph. One wants to know the percent of students bringing `2` pens. Another wants to find if the data value of `3` and `4` are combined, will the result be higher than the data-value of `2`? The bar graph does not help in answering such questions. One would end up using the actual data values.

Considering the number of pens a student carries. The figure provides a form of graph that helps to answer questions that compare a data-value to the whole or combining two or more neighboring data values to compare. This is called pie-chart.

This represents the following as segments in circle

• frequency of `1` is `1`, which is represented as a segment of orange color.

• frequency of `2` is `13`, which is represented as a segment of blue color.

• frequency of `3` is `4`, which is represented as a segment of purple color.

• frequency of `4` is `2`, which is represented as a segment of yellow color.

The total is `1+13+4+2 = 20`.

The word "pie" means: a circular dish, usually cut in angular segments and served.

*familiarize with the terminology *

pie

**Pie Chart** : A representation of data as segments of a circle or a disc.

*Consider the data: • frequency of `1` is `1` • frequency of `2` is `13` • frequency of `3` is `4` • frequency of `4` is `2` The total is `1+13+4+2 = 20`* The circle represents the total `20`. In that case, what is the angle in the segment representing `1`

`= 1 xx 360//20`.

Drawing a pie-chart: The total is `1+13+4+2 = 20` which represents whole circle with `360^@` angle.

• Frequency of `1` is `1`, and that would be represented by a segment with angle `1 xx 360//20 =18^@` angle.

• Frequency of `2` is `13`, and that would be represented by a segment with angle `13 xx 360//20 =234^@` angle.

• Frequency of `3` is `4`, and that would be represented by a segment with angle `4 xx 360//20 =72^@` angle.

• Frequency of `4` is `2`, and that would be represented by a segment with angle `2 xx 360//20 =36^@` angle.

*switch to interactive version*