Roulette probability formula. Then you can use the following formula: Odds for Winning = Probability of Winning / (1 – Probability of Winning). Roulette probability formula

 
 Then you can use the following formula: Odds for Winning = Probability of Winning / (1 – Probability of Winning)Roulette probability formula 1081 Multiply by 100

A gambler plays roulette 15 times, betting on red each time. The probability you will not win at least once after n n spins is. The formula for calculating the Kelly stake is: [(Probability multiplied by odds) – 1] divided by (odds-1) Using the probability mass function and summation notation allows us to more compactly write this formula as follows, where the summation is taken over the index i: E( X ) = Σ x i f ( x i ). e. What is the formula that proves this? Old question, but still unclear and would like to have an answer. e. Interpreting the results of the probability roulette calculator. , A _______ variable is a variable that has a single numerical value, determined by chance, for each outcome of a procedure. Run the simulation 1000 times and compare the empirical density function and moments of \(W\) to the true probability density function and moments. The 1 is the number of opposite choices, so it is: n−k. The game of roulette involves spinning a wheel with 38 slots: 18 red, 18 black, and 2 green. Bayes’s theorem. …Thanks for the compliment. 02 = 1. Let q be the probability of losing (e. Initially 1$ is used. 4759. 41% for European, and 5. The probability of all bets in roulette can be calculated by simple counting. 3%, while the basket. and more. First, let’s explain what the term “probability” actually means. Understanding Roulette Odds and Probability. For DC = 66. With the 5% house edge, players would eventually walk away with 95% of their money. The formula is simply =D6*D5*D4, which multiplies your bankroll times the Kelly recommended bet proportion, multiplied by the adjustment factor you put into D6. In games with one zero the casino’s house edge is 2. In numerical terms. The following image shows how to find the probability that the dice lands on a number between 3 and 6: Statistics and probability 16 units · 157 skills. Someone mentioned that he guessed the correct number five times in a row, and said that this was surprising because the probability of this happening was $$left(frac{1}{38} ight)^5$$ This is true if you only play the game $5$ times. The probability of each pocket is 1/38, so the probability of this event is 4 x 1/38 = 4/38 = 0. 1081 x 100 = 10. The probability of surviving is an, easy to calculate, and very unhealthy, 83. For example, if you bet on 0, you expect to win about 1 in 37 spins (on a single zero wheel) 3. Calculating probabilities in roulette is relatively easy and simply involves using the fraction and dividing and multiplying accordingly. Calculation of Expected Value We use the above information with the formula for expected value. It basically. The shooter bets on whether the chamber which rotates into place will be loaded. The story is about Croatian Niko Tosa, who roamed the world, from casino to casino, beating roulette wheels. The most important part of any Monte Carlo simulation (or any analysis for that matter) is drawing conclusions from the results. , For the binomial. This formula can be applied to determine any roulette probability by using the form of “Bet B hitting x times in n spins. We can no longer use the binomial distribution probability formula in such an instance. According to the internet (so it has to be true), there is a variant of the Russian Roulette problem that is commonly asked as an interview question. This investigation will be using the French version of roulette without the 00 number. This gives b =5/6 a. we would rotate the above roulette wheel at random. In games with one zero the casino’s house edge is 2. 9. (This is the same as the probability of "the roulette hits $5$ reds and a black," which is exactly the point of the first computation. The value used in the numerator of the probability fraction depends on whether you are. . For all bets, the House Edge in American Roulette is 5. 3444 0. The casino game, roulette, allows the gambler to bet on the probability of a ball, which spins in the roulette wheel, landing on a particular color, number, or range of numbers. Since we have a discrete random. (5)( 1 50) = 5 50. n is the number of trials (spins) x is the number of times our bet wins. Question: What is the expected value of net winnings when betting £100 on the number 5 in European roulette? Roulette Probability Formula, Ggv Time Slot September 2018, Borderlands 3 Moxxi Slot Machine, Tonkaaaa Poker, Roulette Animation Powerpoint, Winstar Casino Distance From Dallas, Free Classic Retro Slots At the start of this guide, we listed the top 6 roulette strategies. We have a total of 38 38 slots in which any spin of the wheel may land. The double-zero roulette game has 38 possible cases (36 numbers, plus 0, plus 00). ) 7 The normal curve approximation The area under the normal curve between -. If the probability of matching all 6 numbers is (frac{1}{12271512} approx 0. 1667, or 16. 5(-1)=0. Author: Luke Holmes, Last Updated: 9th December 2022 Knowing the probability of success of your roulette odds is half the battle. Since 5 of the 6 chambers are empty and each has an equal chance of containing the bullet, we get p=5/6. A spinning wheel with 37 or 38 numbered compartments is used. Roulette standard deviation figure assumes player makes even money bets only. 1081 Multiply by 100. 5$, because of a 00 on the wheel. But the formula works only for binary bets where the downside. Therefore, if E (X) = µ, we have E (X − µ) = E (X) − E (µ) = µ − µ = 0. What is the probability that both balls would drop into the same slot?PROBABILITY OF SUCCESS = 1 / 1 + 5 = 1 / 6 = 0. Since there are 52 cards in a deck and 13 of them are hearts, the probability that the first card is a heart is 13 / 52 = 1 / 4. 1. We get that the probability of not drawing a specific number is 36/37. 89% chance of guessing the winning number. Spinning a roulette wheel 9 times, keeping track of the occurrences of winning a number "16. wheel is spun twice and the random variable X is the sum from the two spins. 1) 2 ⋅ 0. A square has four outcomes, so the probability is 4/37. 10. At the Las Vegas roulette (with 38 numbers, 0,00,1,2,3, etc) you can do various bets (let’s say the bet size is $1). Roulette odds and probability are two essential concepts that dictate the outcome of each spin. It is the probability of NOT seeing 0 in x spins. We can calculate the exact probability using the binomial table in the back of the book with n = 10 and p = 1 2. 26% on an American style table). A roulette is a curve traced by a fixed point on a closed convex curve as that curve rolls without slipping along a second curve. After firing (and not getting hit), you can either pull the trigger again (1/5 probability of getting hit. Seal and Przasnyski: Illustrating Probability through Roulette: A Spreadsheet Model Produced by The Berkeley Electronic Press, 2005 The game of roulette is an interesting and intriguing problem. : When you double your bet size, your profit/loss in both the win or loose scenario doubles. The probability of selecting a solution can be given by:. The probability of winning is 1/38 and the probability of losing is 37/38. Solution. 45 goals. The following image shows the probability of a dice landing on a certain value on a given roll: Since the dice is equally likely to land on each value, the probability is the same for each value. If you can bet $1$ dollar and win with a probability of $dfrac{1}{38}$ in a game of roulette. the probability of getting one roulette number is 1 in 38 or p = 1/38. Las Vegas roulette has 38 numbers, 0 and 00 which are green and 1 to 36, half them being red and half of them being black. roulette, the probability that the ball drops into any one slot is 1 out of 38. 473 ≈ . 0278 x 100 = 2. $100,000 – $275 = $99,725. 4747 0. In this article, we will discuss about fitness functions and how to come up with a fitness function for a given problem. , A _______ variable is a variable that has a single numerical value, determined by chance, for each. the probability of getting one point face when rolling a die is 1 in 6 or p = 1 / 6; the probability of getting one roulette number is 1 in 38 or p = 1 / 38. Since the probability of a winning number for a single roll of a die is 1/6, it follows the game has 5 to 1 odds. The probabilities to win or to lose are: P(X =win) P(X =lose) = 18 37 = 19 37 P ( X = w i n) = 18 37 P ( X = l o s e) = 19 37. 0270 x 100 = 2. In summary, the conversation discusses the probability of a specific number appearing multiple times on a roulette wheel in a fixed number of spins. 3 Answers. 21; Therefore, in the above example, it can be seen that the probability of first success decreases with the increase in the number of failed attempts,. So, when we say $10 X 5 = $5. (You do not need to replicate the sample code. Take 1/36 to get the decimal and multiple by 100 to get the percentage: 1/36 = 0. Once your opponent has survived the first round, he or she turns into the player to go first, with probability a of winning the game, so q=a. Let X be the number of wins. For an underdog moneyline to break-even win probability Where A1 contains the moneyline odds (like +140) =1-A1/(A1+100) When this gets evaluated with our example number, you get the following:. (5 – 2. Assume European roulette win single zero. An American roulette wheel has 38 slots; 18 are red, 18 are black, and 2 are green. Then you can use the following formula: Odds for Winning = Probability of Winning / (1 – Probability of Winning). But there's also a fourth- implied probability - that is also useful when evaluating a bet or checking how likely an outcome is. 47) Binomial probability formula is written as:calculate the result of the formula. Bankroll: Game: Blackjack Baccarat Pai gow (tiles) Pai gow poker Roulette (single 0, even money bets) Roulette (double 0, even money bets) Roulette (triple 0, even money bets) Ultimate Texas Hold 'Em Three Card Poker (Ante) Three Card Poker (Pairplus) Craps. Then we subtract probability from 1. pdf), Text File (. 2460. Steps in the Martingale Strategy for Roulette. Unit 6 Study design. e. Here is the file FORMULA generated: The standard deviation for an event of probability p = . 1 Number "Straight Up": 1/382 Roulette wheel. So, if we are covering three numbers with a bet, we have a 7. How large is the probability that the next throw is the number… Some gamblers use a martingale or doubling strategy as a way of improving their chances of winning. First ,break the odds into 2 separate events: the odds of drawing a white marble (11) and the odds of drawing a marble of a different color (9). The calculation of roulette wheel probabilities is very simple. A statistics expert would now interpret the probability of rolling the particular number as one-sixth, while the expert in gambling would say it is 1 chance out of 6. Roulette strategies: Martingale. I'm not sure how to solve this. Roulette Calculator Calculate the roulette probability of (13-24) along with the expected return on your $10. archive. 26% (if you are interested in the mathematics of roulette, the video at the end will show you how these odds are calculated). In the roulette experiment, select the 18-number bet. However, with a payout of only four times the amount wagered (i. 0270. For example, they might see 5 reds in a row and assume red is on a streak. mean (S > 0) Exercise 5. 26% for American roulette. However I think your book. However the actual probability is much less, because as the player gets each blackjack the ratio of aces to cards left in the deck decreases. The shooter bets on whether the chamber which rotates into place will be loaded. Relation of the Birthday Paradox to roulette. What is the probability that the wheel lands on a number divisible by 4 when you roll the roulette?. 1. P(E) = 20/30 = 0. I need a general formula for calculating the probability of an event, given specific parameters: We need to calculate the probability P(e) of the event E = [Bet B appearing X times in N trials(ie. . 6%) but your estimate of the ‘true’ probability of the draw is 30%. Assuming the game is played repeatedly in rounds until some one loses infinitely, what is the average number of trigger pulls before the gun goes off. So if the house edge is 2. Add the numbers together to convert the odds to probability. One thing that makes roulette so popular with gamblers is the game’s transparency. . 18 18 of these are red, and 18 18 of the slots are black. If you chose correctly, the payout would be 2 – 1. A formula for calculating probability from odds is P = O / (O + 1). 3 is the probability of the opposite choice, so it is: 1−p. You decide to play 6 spins of Roulette and bet each time that the ball will land on a red number. for American double-zero roulette, it is 20/38 for a bet on black or red). If it is, he loses not only his bet but his life. Expected value of insurance. There is no other. Example (PageIndex{5}): House Edge in Roulette. Free Roulette Calculator - Calculates the probability for different bets on a roulette wheel including expected return on a monetary bet. 2. Expression using fractions (1 / x) - If we express the probability using a fraction, we say that the phenomenon occurs 1 time from X attempts. The type of roulette has a big impact on the roulette strategy probability. In both of the games I will start with 1000. I'm learning about the gamblers ruin. 34 + 2*0. Try to mix up your bets by placing a combination of two or more outside bets. The results showed that the probability increased with the change in bet amount which meant. . , Is the following a probability model? What. So I have subtracted the $23^{37}$ words that miss the "letter" (roulette number) $1$, also the $23^{37}$ that miss the letter $2$. Round to three decimal places. Unit 2 Displaying and comparing quantitative data. Interpreting the results of the probability roulette calculator: The probability for event A to occur exactly m times in n spins is given by the formula , according to Bernoulli's formula. 60% American Roulette). Dice, Slots, Roulette, Baccarat, Blackjack, Poker, Lottery and Sport Bets Book · August 2006 CITATION 1 READS 1,363 1 author: Some o f the authors of this public ation are also w orking on these r elated projects:. Here is the principal mathematical formula for calculating the chance of any roulette outcome or event. The problem is that I don't know how to calclate the formula. A Scientific Study of Roulette. For example, in Roulette, p = 18 38 = 9 19 ≈ . Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. Q: Find the probability of winning in American-style roulette when betting on the first six numbers, 1… A: Number of wheels in American-style roulette =38 Bet consists of 6 numbers Q: A jar on your desk contains fourteen black, nine red, thirteen yellow, and four green jellybeans. Roulette math: Formula for roulette prediction. , the 1 to 1 odds are exact. It is the probability of a specific sequence of outcomes, where each is independent (my wording might be off). Now let’s calculate the uniform distribution. The odds improve with every additional number added to the bet, but the potential payout goes down. 5. We would interpret it as 16. 11 + 4*0. Bets are placed on individual numbers, colors or sets of numbers, and a ball is spun into the roulette wheel to determine the winner of the bet. g. 3%. 5 probability of losing $1. expand_less. Hence your expected gain/loss doubles. 06 percent. A) The probability p for a single zero roulette game is: p = 1/37 = 0. The probability of at least breaking even and being ahead for various betting options with a 200 unit stake. Let F [p,n,m,v] be the probability of the v-th man losing in the Russian roulette game with p-players, n-chambers and m-bullets. The probability that the zero wins is 1/37, 0. Within our roulette payout calculator, we included multiple types of bets, so you can calculate their respective payouts with the following formula: Payout = (36/S) – 1 where S = the number of spaces covered by your bet. The roulettes described by the foci of conics when rolled upon a line are sections of minimal surfaces (i. 2. But the probably of 33 consecutive blacks is such a low %, you could bet your life it wouldnt happen. e. In this case: number of f avorable outcomes = 1 (30) T otal number of outcomes = 38 (numbers from 1 to 36, also included 0 and 00) Then. Roulette Rules. -The European Roulette is made up of 37 spinning numbers and a ball is thrown which falls into one of them. A game of chance is roulette. Hello I have a basic but quite difficult question about roulette probabilities (assuming roulette has 37 numbers 0-36). Bayes formula: A particular important application of conditional probability is Bayes formula. . g. 89% in American roulette. 10. The probability of an event is a number between 0 and 1, where, roughly speaking, 0 indicates impossibility of the event and 1 indicates certainty. A roulette wheel has slots numbered 1-38 and the number 0. Blackjack payout side bet . Probability with Roulette Probability with Roulette Marshall, Jennings B. Not surprisingly, the expected value is negative; the insurance company can only afford to offer policies if they, on average, make money on. A particularly interesting case of a roulette is a regular n-gon rolling on a. Roulette is a casino game played at a table with a numbered, spinning wheel and betting layout. The formula can be used to calculate the probability of winning all roulette bets. Unit 3 Summarizing quantitative data. Question: What is the expected value of net winnings when betting £100 on the number 5 in European roulette?Roulette Probability Formula, Ggv Time Slot September 2018, Borderlands 3 Moxxi Slot Machine, Tonkaaaa Poker, Roulette Animation Powerpoint, Winstar Casino Distance From Dallas, Free Classic Retro SlotsAt the start of this guide, we listed the top 6 roulette strategies. To find the expected value, use the formula: E (x) = x1 * P (x1) +. g. When studying statistics for data science, you will inevitably have to learn about probability. Possible Outcomes and Sums. The betting area in roulette is known as the layout. a) You watch a roulette wheel spin 7 consecutive times and the ball lands on a red slot each time. 0. The probability of the outcome $36 is 1/38. On cell E9, calculate the appropriate probability of landing on a 0 or 00. This article describes the formula syntax and usage of the HYPGEOM. The variance is the probability-weighted sum of squared distances from the expected value. Compute the probability not to win and use the formula for P(A[B). After Jagger returned to the village of Shelf near Halifax, Yorkshire, he continued toExplain using information you learned in this module's material, such as expected value. 302% 1. To see the Kelly formula in action, let’s take an example of a football match where the odds available on the draw are 3. 26% (if you are interested in the mathematics of roulette, the video at the end will show you how these odds are calculated). At a roulette table, there is a wheel containing 37 possible pockets a ball can land on (each are marked 0, 1, 2, 3, etc. Start the Roulette and when the result is shown, click on the number that appears on this page. 3439. 35. com The essence of the Martingale roulette game system is as follows: we bet on an even chance of roulette (red-black, even-odd), for example, on "red": we bet on roulette at $ 1; if you lose, we double the bet and bet $ 2. Math Probability We know that in a game of U. Answer. org) on March 11, 2000. Just as one die has six outcomes and two dice have 6 2 = 36 outcomes, the probability experiment of rolling three dice has 6 3 = 216 outcomes. It follows that the higher the probability of an event, the more certain it is that the event will occur. This gives you the total number of non-unqiue ways to choose these numbers. For your last question, the probability of getting an odd number on a real roulette wheel is actually less than $0. What is the expected value on a bet such as this? Since there are 18 red spaces there is an 18/38 probability of winning, with a net gain of $1. It is quantified as a number between 0 and 1, with 1 signifying certainty, and 0 signifying that the event cannot occur. Many roulette wheels have slots numbered 0, 00, and 1 through 36. ,Roulette The game of roulette serves as a nice introduction to some of the key ideas relating to probability. 6230 − 0. The probability of getting 3 lemons is 1/10 X 1/10 X 1/10, or 1/1000. Converting odds is pretty simple. If you place a straight bet, you are betting on a single number. spin MISS HIT HIT=1 HIT>1 *MISS = miss all spins *HIT=1 = hit. According to the law, the average of the results obtained from a large number of independent identical trials should be close to the expected value and tends to become closer to the expected. So, the probability of winning when betting on the number 5 in European roulette is 1/37. 1:1 payout means you receive 1 chip PLUS your original bet 5:1 payout means you receive 5 chips PLUS your original bet. If you download the paper, you also get the Mathematica notebook that produced the calculations, and the results. 47 Since, all trials are independent and probability of red in each trials is same which is 0. Dec 22, 2020 The deposit bonuses carry 35x play through requirement. Use the binomial probability formula to find the probability of x successes given the probability p of success on a single trial. Thus, the probability that you win any one round will. $> 105$ dollars) if you currently have $105$ dollars, and thus can make $105$ bets on the wheel? 1 – (1/18 + 1/18) = 8/9 = 0. After launching the Roulette Predictor, the system will indicate the starting bet. g. The letter n denotes the number of trials. 77 The expected (theoretical) number of successes is: 65 Based on the Normal Probability Rule: · 68. If you bet on red the probability to loose is. 2 Answers. We have a combination of two simple events: finding an even. The ball falls into the green slots 5 or more times Probability B. (3) (b) Find the expected value of X, E. spin MISS HIT HIT=1 HIT>1 *MISS = miss all spins *HIT=1 = hit exactly once *HIT = hit at least once *HIT>1 = hit more than once >>INSTRUCTIONS. If a player bets $1 on red or black on an American table (with 0 and 00) there is a probability of 18/38 (47. This gives lower fitness individual higher fitness (pseudo fitness for selection's sake). 4. Players wager on the slot into which the ball will land. On an American wheel, the house advantage is twice that of a European wheel, which means you could lose money twice as fast. So the probability of four in a row is (64/1326) 4 = 16777216/ 3091534492176 = 1 in 184270. 6% chance that exactly five of the ten people selected approve of the job the President is doing. Because of this, the odds of coming out in front in the long-run are very very small, and close enough to impossible. If n = 100 dollars, and m = 100 dollars, then T = 200 dollars. The bet has a low probability of winning matched with a low payout, meaning the house edge is much higher. Let us take the classic example of a dice with the numbers one to six. For example, in American roulette the odds of hitting a single number with a straight-up bet are 37 to 1, since there are 38 numbers. Number of slots on the wheel: 37 (Single-zero) 38 (Double-zero) 39 (Triple-zero) other. 64%. 5 n. European Roulette. The probability of winning n/N games at win probability p is: $$f(n) = p^n(1-p)^{N-n}frac{N!}{n!(N-n)!}$$ Your numbers for these would be 105 and 1/38 for N and p. When it comes to the same number landing. you simply need to use the above-mentioned. David Gustafson, Jeff Hughes. Unit 4 Modeling data distributions. Monday, 16 October 2023 13:19 Written by Martina Maritato Here at Bet and Skill we love a spin of the roulette wheel and know all there is to know about the popular casino game. Get the winner of the electronic raffle with RAND, INDEX, MATCH and MAX functions. =1, to the mind: (5) Since the probability of winning Pwin in the 'European Roulette' while you are playing for N sectors (rooms) is equal to. 5) = $0. What are the odds we win 100 dollars before losing 100 dollars? Most folks would think that since . 5×1+ (2÷3 ) ×1 + . You are tied to a. The odds in roulette indicate your chances of winning a bet. Figure 6. NOT rolling a 5 5 (or any other specific number) Plugging it all in, we get ≈ . The result of 1/37 is 0. Do the outcomes form a sequence of Bernoulli trials? If so, identify the trial outcomes and the parameter (p). 06, which equals a probability of 48. For. 8211765. Since 5 of the 6 chambers are empty and each has an equal chance of containing the bullet, we get p=5/6. 7%. In this paper, we implement a model of roulette in a spreadsheet that can simulate outcomes of. The formula of hypergeometric probability distribution is the most comprehensive calculator of odds and probabilities in lottery and lotto, including Powerball, Mega Millions, Euromillions, Keno. In order to place these numbers into the formula and be able to subtract fractions, we need equal. 5 +1= 8÷3 so avg of both cases is 8. Example (The probability of Red) The probability of the ball landing in Red is. The probability of red is 18 38 = 9 19. This paper derives important formulas for the martingale strategy, such as the distribution, the expected value, the standard deviation of the profit, the risk of a loss or the expected bet of one or multiple martingale rounds. Roulette Probabilities You can use this formula for all types of betting. Is the roulette calculator probability formula accurate enough that we should take it seriously? It is important to keep in mind that the number of pockets on a roulette wheel does not change from spin to spin. Find a formula for the probability distribution of X, the number that occurs when the wheel is spun Answer in Statistics and Probability for Shubham rahul jagt #291629Indeed, it is the most essential formula of theory of probability. If you play 19 numbers in 2 consecutive roulette spins, the probability to win at least once is 75%. The probability of an event is (frac{3}{8}). Martingale is the best-known online roulette strategy to win. a. 45 goals. S. 5. expected value of a discrete random variable. The formula used for the probability of ruin can be found in Blackjack Attack, by Don Schlesinger, 2004 edition, page 132, under "The Short-Term, or Trip, Ruin Formula. Informally, the expected value is the arithmetic mean of a large number of independently selected outcomes of a random variable. 50 (or 5/2 with an implied probability of 28. A simple example: Say you bet $100 on red. In fact, as we will see, we win before we lose with probability at most 1 37648. DIST function in Microsoft Excel. There is a 20/38 probability of losing your initial bet of $1. 1 4 × 1 2 = 1 8. 83 and . One of the famous problems that motivated the beginnings of modern probability theory in the 17th century, it led Blaise Pascal to the first explicit reasoning about what today is known as an expected value. Added to which, the interpretations of probability regarding predictions have always carried a sense of the mystical. (equally likely) outcomes. The house edge largely depends on which type of roulette game you are playing. To apply the formula, we need to follow these steps: Select cell E3 and click on it. , we actually have probabilities of 50 % for a win and 50 % for a loss each time the coin is tossed, i. Roulette Probabilities Calculator. Using simple VBA code and some nice formulas you can do this. You watch a roulette wheel spin 3 consecutive times and the ball lands on a red slot each time. Solution: (a) The repeated tossing of the coin is an example of a Bernoulli trial. Free Roulette Calculator - Calculates the probability for different bets on a roulette wheel including expected return on a monetary bet. $egingroup$ Yes you are right, but for Inclusion/Exclusion, we deal with issues one at a time. Everytime you lose, you double up the stake. We compute the probability of a gamblers ruin with applications to the various betting opportunities playing roulette by determining the W+1 roots of the relevant polynomials and from there. spins) ] We know: N= the. Your formula (1/N)^x does not express the likelihood of any single outcome. Martingale is the best-known online roulette strategy to win. This article specifically deals with the application of Birthday Paradox to the lottery, lotto, and roulette (other forms of gambling as well by extension). The difference is that it is offered in the comfort of your home. The Fibonacci is a popular Roulette betting system that is based on a naturally occurring mathematical sequence. You can have as many x z * P (x z) s in the. The expected value of this bet in roulette is 1 (18/38) + (-1) (20/38) = -2/38, which is about 5.