(2) Please explain the relationship among the concepts of limits，continuity, differentiation, and integration. You can use examples for demonstration in your explanation.

2. If the random variable X is the outcome of throwing a fair dice，then the sample space of X is { 1， 2，3, 4，5, 6}. Please use Riemann-Stieltjes integral to calculate the expectation and variance of X, that is，E[X] andVar[X].