The exam scores in a national assessment follow a normal distribution with mean and standard deviation . What percentage of candidates score between and ?
Answer and explanation
Correct answer: D.
- Step 1: The score interval corresponds to , exactly one standard deviation from the mean. According to the empirical rule for normal distributions, approximately of the data falls within one standard deviation of the mean. **Answer: . Why not the others:** corresponds to two standard deviations , corresponds to scores above or below the mean, and corresponds to three standard deviations .
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