can summation of n stochastic variable be a constant number?

Question

Can we have a summation of $n$ stochastic variables equal to a constant? For example, I have $n$ normal variables which are the time for using different functions of the cell phone of one person. So the total using time is a constant, but the time for using different function is a stochastic variable.

Answer 1

A sum of independent random variables cannot be a constant unless each of them is a constant. Without independence the sum can be a constant: take $X$ and $-X$.