1. An experimental drug has been shown to be 80% effective in eliminating symptoms of allergies in animal studies. A small human study involving eight participants is conducted. What is the probability that the drug is effective on half of the participants?

2. An investigator wants to test whether exposure to secondhand smoke before 1 year of life is associated with development of childhood asthma (defined as asthma diagnosed before 5 years of age). Give two possible study designs.

3. Approximately 35% of obese patients develop diabetes. Answer the following questions if a physician sees 12 patients who are obese. What is the probability that half of them will develop diabetes?

4. A study is run to estimate the incidence of atrial fibrillation (AF) in men and women over the age of 60. Development of atrial fibrillation was monitored over a 10-year follow-up period. The data are summarized below. Using this data, compute the cumulative incidence of AF in men and in women respectively.

	Developed AF	Did not Develop AF
Men	133	6153
Women	79	7167

5. Four hundred melanoma patients were diagnosed according to the type of skin cancer and the location of the skin cancer. This data is presented below. What proportion of patients had Hutchinson's melanomic freckle?

	Location
Type	Head and Neck	Trunk	Extremities	Total
Hutchinson's melanomic freckle	22	2	10	34
Indeterminate	11	17	28	56
Nodular	19	33	73	125
Superficial spreading melanoma	16	54	115	185
Total	68	106	226	400