The Common Formula on Birandom Variable Variance

In order to solve the calculating problem of birandom variable variance, and develop its application, according to uncertainty theory, basing on the theory of birandom variable, we studied the algorithm and its property on birandom variable variance, proved and obtained a series of important formulas. At last, we got the common formula on birandom variable variance. The example shows that the common formula can be used in calculating birandom variable variance, and it is easy to be used. Therefore, the common formula will satisfy the calculating need for birandom variable variance, which is beneficial in the computer information system.