- Chen is treating vines to prevent fungus appearing. One month after the treatment, Chen monitors the vines to see if fungus is present.
The contingency table shows information about the type of treatment for a sample of 150 vines and whether or not fungus is present.
| \multirow{2}{*}{} | Type of treatment |
| None | Sulphur | Copper sulphate |
| No fungus present | 20 | 55 | 48 |
| Fungus present | 10 | 8 | 9 |
Test, at the \(5 \%\) level of significance, whether or not there is any association between the type of treatment and the presence of fungus.
Show your working clearly, stating your hypotheses, expected frequencies, test statistic and critical value.