A student wants to estimate the size of a dandelion population in a 400 m2 playing field. They use a 1 m2 quadrat to sample the field. The table below shows the results for the number of dandelion plants and their mean height across six quadrat samples.
| Sample number | Number of dandelion plants | Mean height of dandelion plants / cm |
|---|---|---|
| 1 | 8 | 12 |
| 2 | 5 | 10 |
| 3 | 9 | 15 |
| 4 | 4 | 8 |
| 5 | 7 | 11 |
| 6 | 9 | 13 |
Calculate the mean number of dandelion plants for the six samples.
