Chapter 6: Problem 13
You have 80 dollars and play the following game. An urn contains two white balls and two black balls. You draw the balls out one at a time without replacement until all the balls are gone. On each draw, you bet half of your present fortune that you will draw a white ball. What is your expected final fortune?
Short Answer
Step by step solution
Initial Setup
Probabilities of Events
Calculating Expected Value After First Draw
Calculation for Second Draw
Consider Outcomes for All Draws
Calculating Total Expected Value
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Expected Value
In our game, you start with $80 and bet on each draw from an urn. The Expected Value combines all possible outcomes by weighing each according to its probability. To determine your final expected fortune, consider each possible sequence of draws:
- Two white balls (WW) resulting in a $160 fortune.
- One white followed by one black (WB) or one black followed by one white (BW), both resulting in return to $80.
- Two black balls (BB) resulting in $0.
Conditional Probability
- Initial draw probabilities are simple, each color having a 1/2 chance.
- Once a ball is drawn, the urn's composition adjusts the likelihood of drawing the next white or black ball.
Betting Strategy
- If you're fortunate, your capital increases significantly when drawing a white ball.
- If a black ball is drawn, your fortune is halved, and careful analysis is needed for the next bet.
Random Draws
The process begins with four balls (two white and two black) and involves random selection, where your decisions influence your overall fortune.
As balls are drawn, the system's behavior shifts, reflecting the chance-driven essence of random draws and illustrating how they evoke chain reactions impacting subsequent draws and final results.