4.7 Discrete random variables

4.7 Discrete random variables Quiz

IB Maths: Analysis and Approaches HL: Quiz

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5 questions, one answer each

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1. $P(X = x) = \frac{x + 1}{k}$ for $x \in \{0, 1, 2, 3\}$ . Find $k$ .
- A. 6
- B. 10
- C. 4
- D. 9
2. $P(X = 1) = 0.2$ , $P(X = 2) = 0.5$ , $P(X = 5) = 0.3$ . Find $E(X)$ .
- A. 2.7
- B. 2.5
- C. 1
- D. 8
3. A game costs 2 dollars. You win 10 dollars with probability 0.1, otherwise nothing. Find the expected gain.
- A. $\text{\textdollar}1$
- B. $-\text{\textdollar}1$
- C. $\text{\textdollar}0$
- D. $-\text{\textdollar}0.20$
4. Which statement is true of a fair game?
- A. The player always wins back the cost
- B. The expected gain is 0
- C. Every outcome is equally likely
- D. The prize equals the cost
5. $P(X=1) = 0.3$ , $P(X=2) = a$ , $P(X=3) = 2a$ . Find $a$ .
- A. 0.7
- B. 0.35
- C. 0.233
- D. 0.1