A student began to calculate the index of diversity for a community of four species. The table shows her working. One column is incomplete.
| Species | Number of individuals (n) | n(n - 1) |
|---|---|---|
| A | 10 | |
| B | 8 | |
| C | 5 | |
| D | 2 |
Complete the final column of the table by calculating n(n - 1) for each species.
[1]
Calculate the index of diversity for this community. Use and show your working.
[2]