1) Arthritis: The CDC reported the survey of randomly chosen americans age 65 and older, which found that 411 of 1012 men and 535 of 1062 women suffered from some type of arthritis.
a) Are the assumptions and situations necessary for inference satisfied? Explain.
b) Create a 95% confidence interval for the difference in the proportions of senior men and women who have this disease.
c) Interpret your interval in this context.
d) Does the confidence interval suggest that arthritis is more likely to afflict women than men? Explain.
2) Ear Infections: a new vaccine was recently tested to see if it could prevent the painful and recurrent ear infections that many infants suffer from. The lancet, a medical journal, reported a study in which babies about a year old were randomly divided into two groups. One group received vaccinations; the other did not.During the following year, only 333 of 2455 vaccinated children had ear infections, compared to 499 of 2452 unvaccinated children in the control group.
a) Are the conditions for inference satisfied?
b) Find a 95% confidence interval for the difference in rates of ear infection.
c) Use your confidence interval to explain whether you think the vaccine is effective.