GATE AG 2012 • Q12 MCQ • 1 Mark

Section 1: Engineering Mathematics

Probability and Statistics

Subtopic: Mean, median, mode and standard deviation

Question Statement:

Approximate percentage of scores that fall within ±σ (standard deviation) of the mean in a normal distribution is:

Options:

  • (A) 34
  • (B) 68
  • (C) 95
  • (D) 99

Official Answer Key:

B

Step-by-Step Solution & Explanation

For a normal distribution, the empirical (68-95-99.7) rule gives ≈68.27% of observations within one standard deviation of the mean, ≈95.45% within two, and ≈99.73% within three. Answer: B.

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