The herb gingkgo biloba is commonly used as a treatment to prevent demnetia. 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 teh gingkgo treatment group 246 later developed dementia and among those in the placebo gropu 277 later developed dementia and among those in teh placebo 277 later deveoped dementia. We want to use 0.01 significance level to test the claim that the gingko is effective in preventing dementia.
A. Test the claim using a hypothesis test.
b. Test the claim by constructing an appropriate confidence interval.
c. Based on teh reslits is ginkgo effective in preventing dementia?