CIE A Level Maths: Probability & Statistics 2复习笔记2.3.2 E(X) & Var(X) (Continuous)
E(X) & Var(X) (Continuous)
What are E(X) and Var(X)?
- E(X)is the?expected?value, or?mean, of a?random?variable X
- E(X) is the same as the population mean so can also be denoted by?μ
- Var (X)?is the?variance?of the continuous random variable?X
- Standard?deviation?is the?square?root?of the?variance
How do I find the mean and variance of a continuous random variable?
How do I calculate E(g(X))?
Worked Example
Exam Tip
- A?sketch?of the graph of y =? f(x) can highlight any?symmetrical?properties which can help reduce the work involved in finding the?mean?and?variance
- Take care with awkward?values?and?negatives?– use the?memory?features on your calculator and?avoid?rounding?until your?final?answer (if rounding at all!)
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