Variance is a statistical measure of how spread out or dispersed a dataset is around its mean. It measures the average squared deviation of each data point from the mean.Mathematically, variance is calculated by taking the average of the squared differences between each data point and the mean. It is expressed as the average of the squared deviations and is typically denoted as σ².The formula for variance is:Variance (σ²) = Σ(x - μ)² / nWhere:- σ²: Variance- Σ: Summation symbol- x: Individual data point- μ: Mean of the dataset- n: Number of data pointsVariance is a useful measure as it provides information about the spread of data points around the mean. A higher variance indicates that the data points are more spread out, while a lower variance suggests that the data points are closer to the mean.However, it is important to note that variance is sensitive to outliers and extreme values, which can significantly affect its value. Therefore, it is often used in conjunction with other statistical measures, such as standard deviation, to better understand the distribution of data.