Answer: 3.43.
- A 3.43
- B 4.00
- C 2.18
- D 5.33
Correct answer: A. 3.43
Explanation: Harmonic mean HM = n / Σ(1/xᵢ). Here: 1/2 + 1/4 + 1/8 = 4/8 + 2/8 + 1/8 = 7/8. HM = 3 ÷ (7/8) = 3 × 8/7 = 24/7 ≈ 3.43. Useful for rates/speeds where equal time (not equal distance) is spent.
In a perfectly normal (bell-shaped) distribution, mean, median, and mode all coincide at the centre; about 68% of data falls within 1 standard deviation of the mean, 95% within 2, and 99.7% within 3 - the empirical rule used to judge how typical or extreme a value is.
Concept context
Mean, median, mode, standard deviation, and data interpretation