Answer: 3.
- A 3
- B 5
- C 2.5
- D 15
Correct answer: A. 3
Explanation: Mean = (1 + 2 + 3 + 4 + 5)/5 = 15/5 = 3.
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