This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Measures of Central Tendency and Distribution, Subject name: Social & Preventive Medicine
Area between one standard deviation on either side of mean in normal distribution curve is: 
Select and explain. 
A. 62%, B. 68%, C. 90%, D. 99%
B: 68%
Answer: B: 68% 
Explanation: Ans. is 'b' i.e. 68% * mean +- 1SD-68.3%* mean +- 2SD-95.4%* mean +- 3SD-99.7%