No, a constant can be regarded as a random variable X, and C has only one value, so its probability of taking C is1; Then c times the probability 1=C, which means that the mathematical expectation of the constant is itself, but the variance is not itself. Constant refers to a specified number and number, such as the ratio of the circumference to the diameter of a circle π, and the expansion coefficient of iron is 0.0000 12.