Which statistic is the square root of the variance?

• A. Variance
• B. Standard Deviation
• C. Interquartile Range
• D. Range

Answer: (B)

The square root of the variance is the standard deviation. Variance averages the squared deviations from the mean, so it’s expressed in squared units and can be hard to interpret. Taking the square root brings it back to the original units of the data, giving a natural measure of how far, on average, observations lie from the mean. The standard deviation describes the typical spread around the mean. The other measures work differently: variance itself uses squared units, the interquartile range focuses on the middle 50% of data and is not tied to the mean, and the range looks at the extreme values (max minus min) and can be heavily influenced by outliers.