The herb ginkgo biloba is commonly used as a treatment to prevent dementia. In a study of the effectiveness of this treatment, 1545 elderly subjects were given ginkgo and 1524 elderly subjects were given a placebo. Among those in the ginkgo treatment group, 246 later developed dementia, and among those in the placebo group, 277 later developed dementia (based on data from "Ginkgo Biloba for Prevention of Dementia," by DeKosky et al., Journal of the American Medical Association, Vol. 300, No. 19). The researchers want you to test the claim that the true population proportion of patients that develop dementia while taking ginkgo biloba is less than that of those on the placebo. Since this is important to these researchers you should only reject H0 if P < 0.01. They also wish for you to give them an interval estimate, at 99%, for the true difference in proportion between the ginkgo group and the placebo group.

Conclusion?

what type of test are we running in Rstudio?