An ecological team investigated the biodiversity of ground beetle communities in a meadow reserve over 10 years following a restoration project. The index of diversity (ddd) for each year was calculated and recorded in the table below.
| Year | Index of diversity (ddd) |
|---|---|
| Year 1 | 2.5 |
| Year 2 | 3.8 |
| Year 3 | 4.2 |
| Year 4 | 3.0 |
| Year 5 | 5.5 |
| Year 6 | 4.2 |
| Year 7 | 3.0 |
| Year 8 | 6.4 |
| Year 9 | 4.2 |
| Year 10 | 5.0 |
The team used the following formula to calculate the index of diversity (ddd):
d=N(N−1)∑n(n−1) d = \frac{N(N-1)}{\sum n(n-1)} d=∑n(n−1)N(N−1)where:
In some years, the recorded values were N=120N = 120N=120 and ∑n(n−1)=3400\sum n(n-1) = 3400∑n(n−1)=3400.
Determine which years had these values. Use the formula and the table provided to show your working.
