A company has been working on three different projects named X, Y, Z for the past three years. The company investment on these projects during this period is tabulated as shown below. The company manager wants to compare the costs of these projects. It would be easy for him to compare the data, if the data is represented pictorially.
| YEAR | Project X | Project Y | Project Z |
|---|---|---|---|
| 1993 | $10000 | $12000 | $15000 |
| 1994 | $15000 | $10000 | $14000 |
| 1995 | $9000 | $20000 | $17000 |

The above diagrams are called pie charts. In these charts the circle represents the total investment in that year and each color represents the percentage of the total investment on the particular project.
The bar charts give more information than the pie charts as they give the actual numbers rather than the percentages. There are many other ways of representing this data. We can use this data to find many useful statistical measures like mean, variance, mode etc.. which we are going into see in next pages.