Linear functions of a DRV

Linear functions of a DRV Quiz

Spec SA5 · AQA A-Level Further Maths: Quiz

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5 questions, one answer each

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1. $E(X)=3$ . Find $E(4X-1)$ .
- A. $12$
- B. $8$
- C. $11$
- D. $13$
2. $\mathrm{Var}(X)=5$ . Find $\mathrm{Var}(2X+7)$ .
- A. $20$
- B. $10$
- C. $27$
- D. $17$
3. $\mathrm{Var}(X)=2$ . Find $\mathrm{Var}(-3X)$ .
- A. $-6$
- B. $6$
- C. $-18$
- D. $18$
4. The standard deviation of $X$ is $2$ . What is the standard deviation of $5-X$ ?
- A. $-2$
- B. $2$
- C. $3$
- D. $4$
5. Which quantity is unchanged when $b$ in $Y=aX+b$ changes?
- A. The mean
- B. The mode
- C. The variance
- D. The median