An ecologist investigating the health of a deep freshwater lake believes that the concentration of dissolved oxygen, CCC (mg/L), decreases as the depth, zzz (m), increases. To test this, the ecologist measures the oxygen concentration at eight different depths. The data are shown in the table below.
| Depth zzz (m) | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 |
|---|---|---|---|---|---|---|---|---|
| Oxygen CCC (mg/L) | 9.8 | 10.5 | 8.1 | 8.4 | 7.0 | 7.2 | 5.4 | 5.9 |
Calculate Spearman's rank correlation coefficient between zzz and CCC.
Stating your hypotheses clearly, test at the 5% level of significance whether or not the data provide support for the ecologist's belief that oxygen concentration decreases as depth increases.
278 exam-style questions on CCEA A Level Maths 2.5 Data presentation and interpretation, covering 2.5.1 Data presentation and interpretation, 2.5.2 Data presentation and interpretation, 2.5.3 Data presentation and interpretation, 2.5.4 Data presentation and interpretation, 2.5.5 Data presentation and interpretation, 2.5.6 Data presentation and interpretation, 2.5.7 Data presentation and interpretation, 2.5.8 Data presentation and interpretation, 2.5.9 Data presentation and interpretation, and 2.5 Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.