How do I go about calculating the expected profit/winning per play of this game

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Discussion Overview

The discussion revolves around calculating the expected profit or winning per play of a game designed for a data class. Participants explore the game's structure, which consists of three rounds with varying probabilities of winning and losing, and they attempt to apply concepts similar to those used in lottery ticket profit calculations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant describes the game mechanics, detailing the costs and probabilities associated with each round, and expresses difficulty in calculating expected profit.
  • Another participant suggests using a Monte Carlo simulation to verify the expected profit calculation.
  • A participant emphasizes the importance of labeling columns in the calculations to clarify the outcomes and ensure all possibilities are accounted for.
  • There are suggestions to ensure that the probabilities of all possible outcomes add up to 1 and to list these outcomes clearly.
  • One participant points out a potential mistake in the probability assignments related to winning amounts, suggesting that the probability of winning $100 should be twice that of winning $110.
  • Another participant mentions the possibility of double counting the $10 win and recommends focusing on expected winnings rather than losses to simplify the calculation.
  • Participants share their calculations, with one arriving at an expected profit of $-17.083333 per play after adjusting the probabilities and subtracting the initial stake.

Areas of Agreement / Disagreement

Participants express various viewpoints on the correct approach to calculating expected profit, with some agreeing on the need to adjust probabilities and clarify calculations, while others raise concerns about potential mistakes. The discussion remains unresolved regarding the exact expected profit calculation.

Contextual Notes

Participants note the importance of ensuring that all probabilities are accounted for and that calculations are clear, indicating potential limitations in the initial setup of the problem.

hamza2095
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I designed this game for my Data class but I'm having a lot of trouble calculating the expected profit per play of this game. We have taken up examples involving lottery tickets in which you have to calculate the profit and winning per ticket bought but I can't seem to apply the same concepts to my game due to the various stages and rules.

This is how the games goes

You pay $20 to start and there are three rounds

Round 1: There is a 1/2 chance you win and move on, and a 1/2 chance you lose

Round 2: There is a 2/6 chance you move on to the next round, and 1/6 chance you win $10 AND move on. (3/6 chance you lose and get nothing)

Round 3: There is 1/12 chance you win $100, and if you lose you get nothing

Here is my attempt at it

Izn2V.png

After multiplying every correlating x and y value i get E(X) = -18.5, meaning the profit the ones running the game make is $18.5

Help is greatly appreciated!
 
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He best way to check something like this is to run a Monte Carlo simulation with a million trials or so.
 
It would help if you labeled the columns so that it is clear what series of results each represents. I am not sure what the 3'rd column ( -10, 1/12 ) represents. They should all be labeled so you can check that all the possibilities are accounted for exactly once.
 
hamza2095 said:
Here is my attempt at it

You should do an analysis where the probabilities of the possible outcomes add up to 1.

List all the different experiences a player may have and the probability of each of those experiences. Those probabilities should add up to 1 if you have made a complete list.
 
hamza2095 said:
I designed this game for my Data class but I'm having a lot of trouble calculating the expected profit per play of this game. We have taken up examples involving lottery tickets in which you have to calculate the profit and winning per ticket bought but I can't seem to apply the same concepts to my game due to the various stages and rules.

This is how the games goes

You pay $20 to start and there are three rounds

Round 1: There is a 1/2 chance you win and move on, and a 1/2 chance you lose

Round 2: There is a 2/6 chance you move on to the next round, and 1/6 chance you win $10 AND move on. (3/6 chance you lose and get nothing)

Round 3: There is 1/12 chance you win $100, and if you lose you get nothing

Here is my attempt at it

Izn2V.png

After multiplying every correlating x and y value i get E(X) = -18.5, meaning the profit the ones running the game make is $18.5

Help is greatly appreciated!

There an obvious mistake, in that the probability of winning $100 should be twice that of winning $110. You have it as three times.

I also think you may be double counting the $10 win.

It's better to keep the losses out of it. Just calculate the expected winnings per game. Then subtract this from the $20 stake.
 
PeroK said:
There an obvious mistake, in that the probability of winning $100 should be twice that of winning $110. You have it as three times.

I also think you may be double counting the $10 win.

It's better to keep the losses out of it. Just calculate the expected winnings per game. Then subtract this from the $20 stake.
Thank you. I made a chart saying there is a (1/2)(1/6) = 1/12 chance to win $10, and that there is a (1/2)(3/6)(1/12) = 1/48 chance to win $100

after multiplying the prizes and subtracting the starting fees ($20) I got $-17.083333 per play.
 
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hamza2095 said:
Thank you. I made a chart saying there is a (1/2)(1/6) = 1/12 chance to win $10, and that there is a (1/2)(3/6)(1/12) = 1/48 chance to win $100

after multiplying the prizes and subtracting the starting fees ($20) I got $-17.083333 per play.
That's what I got also.
 

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