Math Problem Statement

Jim loves to play roulette! He bets $10 on a single number, usually the number 13. He has a 138 chance of winning. If the ball lands on his number, he wins $350 (and gets to keep his $10 bet!). If it lands on any other number, a 3738 probability, he loses his bet. What is the expected value of a game of roulette?

Round to the nearest cent. Do not round until your final answer. 

Solution

To calculate the expected value (EV) of Jim's roulette game, we can break it down using the given probabilities and outcomes.

  1. Winning Scenario:

    • Probability of winning (landing on 13): P(Win)=138P(\text{Win}) = \frac{1}{38}
    • Winnings: $350 (plus his $10 bet back, for a total of $360)
    • Expected value from winning:
      EVwin=P(Win)×Winnings=138×360EV_{\text{win}} = P(\text{Win}) \times \text{Winnings} = \frac{1}{38} \times 360
  2. Losing Scenario:

    • Probability of losing (landing on any other number): P(Lose)=3738P(\text{Lose}) = \frac{37}{38}
    • Loss: $10
    • Expected value from losing:
      EVlose=P(Lose)×Loss=3738×(10)EV_{\text{lose}} = P(\text{Lose}) \times \text{Loss} = \frac{37}{38} \times (-10)
  3. Total Expected Value:

    • Combine both scenarios: EV=EVwin+EVloseEV = EV_{\text{win}} + EV_{\text{lose}} EV=(138×360)+(3738×(10))EV = \left(\frac{1}{38} \times 360\right) + \left(\frac{37}{38} \times (-10)\right)

Let's calculate this step by step.

Step 1: Calculate EVwinEV_{\text{win}}

EVwin=138×360=360389.47368421EV_{\text{win}} = \frac{1}{38} \times 360 = \frac{360}{38} \approx 9.47368421

Step 2: Calculate EVloseEV_{\text{lose}}

EVlose=3738×(10)=370389.73684211EV_{\text{lose}} = \frac{37}{38} \times (-10) = \frac{-370}{38} \approx -9.73684211

Step 3: Calculate Total Expected Value

EV=9.473684219.736842110.26315790EV = 9.47368421 - 9.73684211 \approx -0.26315790

Final Result

Rounding to the nearest cent: Expected Value0.26\text{Expected Value} \approx -0.26

Thus, the expected value of a game of roulette for Jim is approximately -$0.26.

Would you like more details or have any questions? Here are some related questions you might consider:

  1. What factors can influence the outcome in a game of roulette?
  2. How does the house edge affect expected value in casino games?
  3. What is the difference between American and European roulette?
  4. How can understanding expected value help in gambling decisions?
  5. What are some strategies players use in roulette?

Tip: Always understand the probabilities involved before placing bets in games of chance!

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Math Problem Analysis

Mathematical Concepts

Probability
Expected Value
Basic Statistics

Formulas

EV_win = P(Win) × Winnings
EV_lose = P(Lose) × Loss
Total EV = EV_win + EV_lose

Theorems

Law of Total Expectation

Suitable Grade Level

Grades 9-12