Answer: 2√2.
- A 2
- B 2√2
- C 3
- D 4
Correct answer: B. 2√2
Explanation: Mean = 6; squared deviations 16, 4, 0, 4, 16 sum to 40; variance 8; SD = √8 = 2√2.
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