Об одном подходе к объяснению студентам-нематематикам, что такое ожидание случайной величины
It is clear how to tell students of mathematical specializations what an expectation of a random variable is. These students know Lebesgue integral and Stieltjes integral. Other students know only Riemannian integral often. It is generally accepted to give two different definitions in this case. An expectation of a discrete random variable is defined as a sum and an expectation of a continuous random variable is defined as an integral. But one definition is better than two different definitions. What is more, there are random variables that are neither discrete nor continuous. An expectation is not defined for such random variables in this case. At last, for continuous random variables it is not possible to prove that an expectation of a sum of random variables is equal to the sum of expectations when the expectation is defined as an integral of the probability density function. In this paper, an approach to definition of an expectation of a random variable is suggested that is suitable for students of non-mathematical specializations. This approach has not some of the mentioned drawbacks.