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
In a normal surve, what percent of the values will be included in the area between two standard detions on either side of the mean (x+- ....) ? 
Select and explain. 
A. 68.3, B. 90.4, C. 95.4, D. 99.7
C: 95.4
Answer: C: 95.4 
Explanation: <p> 95.4%. Reference:Park&;s textbook of preventive and social medicine,K.Park,23rd edition,page no:849. <\p>