This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
confidence limits can be calculated using - 
Select and explain. 
A. Mean and range, B. Mean and standard error, C. Median and range, D. Median and standard detion
D: Median and standard detion
Answer: D: Median and standard detion 
Explanation: - the area of either side of mean in normal distribution curve gives the confidence limit. - confidence limit is calculated from mean and standard detion. - 95 percent confidence limits is 2 standard detion added and subtracted from the mean. Reference : Park's textbook of preventive and social medicine, 23rd edition, pg no:849