In statistical theory, covariance is a measure of how much two random variables change together. In other words, covariance is a measure of the strength of the correlation between two random variables. Also, it can be considered as a generalization of the concept of variance of two random variables.
Facts & Figures. Lake Baikal is the largest freshwater lake by volume (23,600km3), containing 20% of the world's fresh water. At 1,637m, it is the deepest freshwater lake in the world; the average depth is 758m. It is 636km long and 81km wide; the surface area is 31,494km2. The lake is estimated to be 25 million years old, making it one of the most ancient lakes in geological history.
  The world's largest lake is the Caspian Sea which â¦ is completely enclosed by Russia, Iran, Kazakhstan, Turkmenistan and Azerbaijan.   The world's deepest lake is Lake Baikal in Siberia, Russia, at 1,638 metres deep.