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A roulette wheel has the numbers 1 through 36,0 , and \(00 .\) A bet on two numbers pays 17 to 1 (that is, if one of the two numbers you bet comes up, you get back your \(\$ 1\) plus another \(\$ 17\) ). How much do you expect to win with a \(\$ 1\) bet on two numbers? HINT [See Example 4.]

Short Answer

Expert verified
The expected value of a \$1 bet on two numbers in a roulette wheel is approximately -\$0.0526. This means, on average, you can expect to lose about 5.26 cents for every dollar bet.

Step by step solution

01

Determine the probability of winning and losing the bet

We have 38 possible outcomes in total when spinning the roulette wheel (1-36, 0, and 00). If we place a bet on any two numbers, there are 2 winning outcomes and 36 losing outcomes. The probability of winning the bet is the ratio of winning outcomes to the total outcomes, while the probability of losing the bet is the ratio of losing outcomes to the total outcomes. Probability of winning (P(W)) = \(\frac{2}{38}\) Probability of losing (P(L)) = \(\frac{36}{38}\)
02

Calculate the winnings for each case

1. If you win the bet, you get back your \(1 plus another \)17. Therefore, the net winnings for the winning case will be $17. Net winnings for winning case = $17 2. If you lose the bet, you lose your \(1, so the net winnings for the losing case will be -\)1. Net winnings for losing case = -$1
03

Use the expected value formula

To find the expected value (EV) of the bet, we multiply the probability of each outcome by its respective net winnings and sum the products. Expected value (EV) = P(W) * Net winnings for winning case + P(L) * Net winnings for losing case EV = \(\frac{2}{38}\) * \(17 + \(\frac{36}{38}\) * (-\)1)
04

Calculate the expected value

Now, we can compute the expected value of the bet. EV = \(\frac{2}{38} * 17 + \frac{36}{38} * (-1)\) EV ≈ -0.0526 So, when placing a \(1 bet on two numbers, on average, you can expect to win approximately -\)0.0526, which means you can expect to lose about 5.26 cents for every dollar bet.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Expected Value
When it comes to understanding probabilities in games like roulette, expected value (EV) is a central concept. Expected value tells you how much you can expect to win or lose on average if you were to repeat a given betting scenario countless times. The core idea is simple: you multiply the probability of each outcome by its respective monetary gain or loss, then sum these values.

In mathematical terms, it’s expressed as:
  • EV = P(Winning) * Net Winnings in Case of Win + P(Losing) * Net Winnings in Case of Loss
Here, net winnings are the difference between the amount you win for a positive outcome and the amount you lose for a negative one. If the expected value is negative, as it is in this exercise, it suggests that on average you stand to lose by making that bet. Remember, expected value helps evaluate risk and potential reward, but it doesn't determine what will happen, just what's likely in the long run.
Roulette
Roulette is a popular casino game of chance, where players can place bets on numbers, groups of numbers, or other possible outcomes. A standard American roulette wheel has 38 slots: numbers 1 through 36, plus 0 and 00. These numbers are distributed evenly and colored red and black, except for the 0s, which are green.

Each spin of the wheel is independent, meaning previous spins do not influence future results. This randomness is what makes roulette exciting, yet it also means outcomes can't be predicted with certainty.
  • The main goal of each spin is to predict where the ball will land.
  • Some common betting options include betting on a single number, a color, or a group of numbers.
Roulette's structure gives the house an edge due to the existence of the 0 and 00 slots, which often leads to a slightly negative expected value for most bets.
Betting Outcomes
In roulette, when you place a bet, there are generally only two outcomes: you win or you lose. The specific terms for winning or losing depend on the type of bet you place. In this exercise, the bet is on two numbers.

The outcomes can be broken down as:
  • Winning Outcome: You bet on two numbers, and the ball lands on one of them. This outcome pays out at 17 to 1, meaning a successful $1 bet returns $18 ($17 in winnings plus your original $1 bet).
  • Losing Outcome: Any result other than those two numbers would result in you losing your $1 bet.
Understanding the different outcomes and their probabilities helps in calculating the expected value and making informed decisions.
Probability Calculation
Probability plays an essential role in predicting outcomes in games of chance like roulette. It measures the likelihood of a specific event occurring. In our exercise, probabilities were calculated for winning and losing a two-number bet.

Here's how you can break it down:
  • Total possible outcomes per spin: 38 (numbers 1 to 36, plus 0 and 00)
  • Probability of Winning: Two favorable outcomes (where the ball lands on one of your chosen numbers), expressed as a fraction: \( \frac{2}{38} \).
  • Probability of Losing: All other outcomes, given as \( \frac{36}{38} \).
These probabilities help determine the expected value and thus the bet's profitability. Probability calculation is about building an understanding of how likely various results are, which is crucial for making strategic bets in roulette.

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Most popular questions from this chapter

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