Answer: Spread of middle 50% of data.
- A Total range from minimum to maximum
- B Spread of middle 50% of data
- C Average spread across the entire dataset
- D Variance, the squared average deviation
Correct answer: B. Spread of middle 50% of data
Explanation: IQR measures the range of the middle 50% of data, making it resistant to outliers.
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