The square root of the variance is called the . . . . . . . . deviation.

The correct answer is D. standard deviation.

The standard deviation is a measure of how spread out numbers are in a data set. It is calculated by taking the square root of the variance. The variance is a measure of how much variation there is from the mean.

The standard deviation is often used to measure the risk of an investment or the uncertainty of a prediction. It is also used to compare the variability of two or more data sets.

A. Empirical is not a measure of variability. It is a measure of the likelihood that a hypothesis is true.

B. Mean is the average of a data set. It is not a measure of variability.

C. Continuous is a type of data. It is not a measure of variability.