Math Problem Statement

A numbers game run by many state governments allows a player to select a two-digit number from 00 to 99. There are 100 such numbers. A bet of $17 is placed on a number. If the number is selected, the player wins $400. If any other number is elected, the player wins nothing. Find the expected value of the game for the player.

Solution

The expected value (EV) of the game is calculated by taking the weighted average of all possible outcomes, where the weights are the probabilities of each outcome.

Problem Breakdown:

  1. Possible outcomes:

    • Win: The player wins $400 if their chosen number is selected.
    • Loss: The player wins $0 if any other number is selected.
  2. Probabilities:

    • Probability of winning: P(Win)=1100P(\text{Win}) = \frac{1}{100}.
    • Probability of losing: P(Loss)=1P(Win)=99100P(\text{Loss}) = 1 - P(\text{Win}) = \frac{99}{100}.
  3. Net gains/losses:

    • If the player wins, they receive $400, but since they paid $17 to play, their net gain is 40017=383400 - 17 = 383.
    • If the player loses, they gain nothing and lose their $17, so the net loss is 17-17.
  4. Expected value formula: EV=P(Win)×Net Gain (Win)+P(Loss)×Net Loss (Loss)EV = P(\text{Win}) \times \text{Net Gain (Win)} + P(\text{Loss}) \times \text{Net Loss (Loss)}

Calculation:

EV=(1100)×383+(99100)×(17)EV = \left(\frac{1}{100}\right) \times 383 + \left(\frac{99}{100}\right) \times (-17)

Step-by-step computation:

  1. First term: 1100×383=3.83\frac{1}{100} \times 383 = 3.83
  2. Second term: 99100×(17)=16.83\frac{99}{100} \times (-17) = -16.83
  3. Combine: EV=3.8316.83=13EV = 3.83 - 16.83 = -13

Conclusion:

The expected value of the game is 13-13 dollars. This means, on average, the player loses $13 per game.


Would you like further details or clarification? Here are five related questions to consider:

  1. How would the expected value change if the prize amount were increased?
  2. What is the probability of winning if the number pool changes (e.g., to 1,000 numbers)?
  3. How does the expected value inform whether the game is fair for players?
  4. Could changing the bet amount impact the expected value? Why or why not?
  5. What is the house edge in this game?

Tip: When analyzing games of chance, consider the expected value to determine whether the game favors the player or the house.

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Math Problem Analysis

Mathematical Concepts

Probability
Expected Value
Weighted Averages

Formulas

Expected Value formula: EV = P(Win) × Net Gain (Win) + P(Loss) × Net Loss (Loss)

Theorems

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Suitable Grade Level

Grades 9-12