S1.5.3 - Mean and variance of a discrete

Mean and variance of a discrete Use of E(X), E(X 2) for calculating the variance of X. random variable.; Knowledge and use of E(aX + b) = aE(X) + b, Var(aX + b) = a2 Var(X).

Use mean and variance of a discrete to connect the rule to the data and decision in the question.

This matters because mean and variance of a discrete determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply mean and variance of a discrete to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: Mean and variance of a discrete is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.