Question

1) In one flu season, the probability of contracting influenza is 16% in unvaccinated healthy adults aged 18-64. A candidate influenza vaccine reduces the probability of contracting influenza to 6% in healthy adults aged 18-64. What is the odds ratio of contracting influenza for vaccinated compared to unvaccinated adults aged 18-64?

2)If you flip three coins, what is the probability that only one coin turns up heads?

3)Suppose you flip three coins and I tell you that there is at least one heads. What is the probability that you observe exactly one heads?

Please help me to solve these problems, and I would like to know the process of how to do these questions. Thank you.

Answer 1