The following are multiple choice questions (with answers) about medical knowledge.   **Question:** The prevalence of disease in a population is expected to be 50%. An investigator is interested in the range of 45 to 55% with 95% confidence. The minimum sample size required for the study is:   (A) 100   (B) 200   (C) 300   (D) 400
['(D) 400 <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) 100 \n (B) 200 \n (C) 300 \n (D) 400 <> possible answers', '  The prevalence of disease in a population is expected to be 50%. An investigator is interested in the range of 45 to 55% with 95% confidence. The minimum sample size required for the study is: <> context@']