In a large population, systolic blood pressure follows a normal distribution with mean 120 mmHg and SD 12 mmHg. Approximately what percentage of individuals will have systolic BP between 96 and 144 mmHg?
- A 68%
- B 80%
- C 95% ✓
- D 99.7%
Correct answer: C. 95%
Explanation
By the empirical rule of the normal distribution, approximately 68% of values lie within 1 SD of the mean, 95% within 2 SD, and 99.7% within 3 SD. The limits 96 and 144 mmHg correspond exactly to 120 minus and plus 24 mmHg, which is 2 SD, so about 95% of individuals fall in this range. Choosing 68% would apply the 1 SD rule, and 99.7% corresponds to 3 SD limits of 84 to 156 mmHg.
Reference: Mahajan's Methods in Biostatistics for Medical Students and Research Workers, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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