Students investigated the population of snails in a freshwater pond over 8 weeks.
The table below shows the number of snails found in four different samples:
| Sample number | 0 weeks | 2 weeks | 4 weeks | 6 weeks | 8 weeks |
|---|---|---|---|---|---|
| 1 | 12 | 10 | 8 | 5 | 2 |
| 2 | 16 | 13 | 11 | 6 | 3 |
| 3 | 20 | 18 | 14 | 10 | 4 |
| 4 | 14 | 11 | XXX | 7 | 3 |
| Totals | 62 | 52 | 42 | 28 | 12 |
Calculate the value of X X\,X which represents the number of snails in sample 4 at 4 weeks.
Calculate the percentage of the snails that were found in the pond at 6 weeks compared with 0 weeks. Give your answer to 1 decimal place.
63 exam-style questions on AQA GCSE Biology 7.1 Adaptations, interdependence and competition, covering 7.1.1 Communities, 7.1.2 Abiotic factors, 7.1.3 Biotic factors, and 7.1.4 Adaptations. Each one has a worked solution and a mark scheme showing where the marks go.