Suppose an influenza vaccine trial carried out during an epidemic. Of 460 adults who took part, 240 received influenza vaccine and 220 received placebo. Overall, 100 people contracted influenza, of whom 20 were in the vaccine.

1. Prepare the contingency table using above information. Describe your findings.
2. Plot an appropriate graph for these variables.
3. Which statistical test is appropriate to use on these data? Give reason.

Test at the 5% level of significance to determine if the vaccine is effective

[hint: for part 3, all five steps as hypotheses, critical value, test statistics, Decision about null hypothesis, and Conclusion]