In a normally distributed population of serum sodium levels with mean 140 mEq/L and standard deviation 5 mEq/L, approximately what percentage of individuals have values between 130 and 150 mEq/L?
- A 95% ✓
- B 68%
- C 99.7%
- D 81.5%
Correct answer: A. 95%
Explanation
The range 130 to 150 mEq/L spans mean plus or minus 2 SD (140 plus or minus 10). By the empirical rule for normal distributions, approximately 95% of observations fall within 2 standard deviations of the mean. Option B corresponds to plus or minus 1 SD. Option C corresponds to plus or minus 3 SD. Option D has no standard empirical rule basis.
Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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