1. **State the problem:** We have three gemstones worth 10, 100, and 1000 respectively. We draw two without replacement and want to find the expected value of the total value $H$ of the two drawn gemstones.
2. **Formula for expected value:** The expected value $E(H)$ is the sum of each possible outcome multiplied by its probability:
$$E(H) = \sum (\text{value of outcome} \times \text{probability of outcome})$$
3. **List all possible pairs and their values:**
- Gemstones: 10, 100, 1000
- Possible pairs (order does not matter):
- (10, 100) with total value $10 + 100 = 110$
- (10, 1000) with total value $10 + 1000 = 1010$
- (100, 1000) with total value $100 + 1000 = 1100$
4. **Calculate probabilities of each pair:**
- Total ways to choose 2 out of 3: $\binom{3}{2} = 3$
- Each pair is equally likely with probability $\frac{1}{3}$
5. **Calculate expected value:**
$$E(H) = 110 \times \frac{1}{3} + 1010 \times \frac{1}{3} + 1100 \times \frac{1}{3} = \frac{110 + 1010 + 1100}{3} = \frac{2220}{3} = 740$$
**Final answer:** The expected value of the total value $H$ of the two gemstones drawn is $740$.
Expected Value Gems 01C219
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