Dice Game Ea7493
1. **Problem Statement:** You pay 1 to play a game where two fair dice are rolled. You win 3 if the sum is 6, 7, or 8; you win 5 if the sum is 2 or 12; otherwise, you lose your 1.
2. **Goal:** Calculate the expected value (EV) of this game to determine if it is favorable.
3. **Step 1: Possible sums and their probabilities.** The sums of two dice range from 2 to 12. The number of ways to get each sum out of 36 total outcomes is:
- 2: 1 way
- 3: 2 ways
- 4: 3 ways
- 5: 4 ways
- 6: 5 ways
- 7: 6 ways
- 8: 5 ways
- 9: 4 ways
- 10: 3 ways
- 11: 2 ways
- 12: 1 way
4. **Step 2: Calculate probabilities:**
- $P(2) = \frac{1}{36}$
- $P(6) = \frac{5}{36}$
- $P(7) = \frac{6}{36}$
- $P(8) = \frac{5}{36}$
- $P(12) = \frac{1}{36}$
- Other sums combined probability = $1 - (P(2)+P(6)+P(7)+P(8)+P(12)) = 1 - \frac{18}{36} = \frac{18}{36}$
5. **Step 3: Calculate expected winnings:**
- Win 3 for sums 6,7,8: $3 \times (P(6)+P(7)+P(8)) = 3 \times \frac{16}{36} = \frac{48}{36}$
- Win 5 for sums 2,12: $5 \times (P(2)+P(12)) = 5 \times \frac{2}{36} = \frac{10}{36}$
- Lose 1 for other sums: $-1 \times \frac{18}{36} = -\frac{18}{36}$
6. **Step 4: Total expected value:**
$$EV = \frac{48}{36} + \frac{10}{36} - \frac{18}{36} = \frac{40}{36} = \frac{10}{9} \approx 1.11$$
7. **Step 5: Interpretation:** The expected value is about 1.11, meaning on average you win 1.11 per game. Since you pay 1 to play, your net expected gain is $1.11 - 1 = 0.11$, so the game is favorable.
**Final answer:** The expected net gain per game is approximately 0.11, so it is a favorable game to play.