In a population, birth weights are normally distributed with a mean of 3000 g and a standard deviation of 400 g. Approximately what percentage of newborns weigh between 2200 g and 3800 g?
- A 95% ✓
- B 68%
- C 99.7%
- D 81.5%
Correct answer: A. 95%
Explanation
By the empirical rule for normal distributions, approximately 95% of observations lie within two standard deviations of the mean. Here 3000 plus or minus 2 times 400 gives 2200 to 3800 g. Option B corresponds to plus or minus 1 SD. Option C corresponds to plus or minus 3 SD. Option D is a distractor with no statistical basis.
Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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