/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 8 This exercise shows that the odd... [FREE SOLUTION] | 91Ó°ÊÓ

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This exercise shows that the odds are hardly ever 'evens' when it comes to dice rolling. (a) Gamblers \(A\) and \(B\) each roll a fair six-faced die, and \(B\) wins if his score is strictly greater than \(A\) 's. Show that the odds are 7 to 5 in A's favour. (b) Calculate the probabilities of scoring a total \(T\) from two rolls of a fair die for \(T=2,3, \ldots, 12 .\) Gamblers \(C\) and \(D\) each roll a fair die twice and score respective totals \(T_{C}\) and \(T_{D}, D\) winning if \(T_{D}>T_{C} .\) Realising that the odds are not equal, \(D\) insists that \(C\) should increase her stake for each game. \(C\) agrees to stake \(£ 1.10\) per game, as compared to D's \(£ 1.00\) stake. Who will show a profit?

Short Answer

Expert verified
The odds are 7 to 5 in A's favor. Gambler D would typically show a profit given enhanced stake values on outcomes.

Step by step solution

01

Understanding Problem (a)

Identify the problem—Gamblers A and B each roll one six-faced die. B wins if his score is greater than A's, and we need to calculate the odds in A's favour.
02

Calculate Total Possible Outcomes for One Roll

Each die has 6 faces, so a pair of dice rolls results in a total of possible outcomes: \(6 \times 6 = 36\) outcomes.
03

Count Winning Outcomes

Let’s find the number of outcomes where B wins by comparing individual dice scores: - If A rolls 1, B can roll 2, 3, 4, 5, 6 (5 outcomes)- If A rolls 2, B can roll 3, 4, 5, 6 (4 outcomes)- If A rolls 3, B can roll 4, 5, 6 (3 outcomes)- If A rolls 4, B can roll 5, 6 (2 outcomes- If A rolls 5, B can roll 6 (1 outcome)Thus, total winning outcomes for B: \(5 + 4 + 3 + 2 + 1 = 15\) outcomes.
04

Calculate A’s Winning Outcomes

Out of the 36 outcomes, 15 result in B winning, 6 are ties where A and B score the same, and the remaining outcomes (36 - 15 - 6 = 15) are where A wins. Thus, A and B each have 15 winning outcomes; ties are not included when measuring odds.
05

Determine Odds

Odds are given as winning to losing outcomes. So, for A: • Wins: 21 (Considering ties favorably to both)• Losses: 15Therefore, odds in A's favor are 7 to 5.
06

Understanding Problem (b)

Identify the problem—Gamblers C, and D each rolling a six-faced die twice. D wins if his score (\(T_D\) is greater than C's (\(T_C\)), Calculate odds and determine expected profit when C stakes £1.10 and D stakes £1.00.
07

Calculate Probabilities of Scoring Total T

Tabulate probabilities for all possible totals from two dice rolls (2 to 12):- Possible totals: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12\(P(T = x) = \determine possibilities for x\ / 36\)- E.g., probabilities for totals: 2: 1/36, 3: 2/36, 4: 3/36, 5: 4/36, 6: 5/36, 7: 6/36, 8: 5/36, 9: 4/36, 10: 3/36, 11: 2/36, 12: 1/36
08

Compute Probabilities of TC > TD

Using the detailed probabilities for each, compute the probability \[T_D > T_C\]. Calculate each combination together, with the sums and resultant probabilities mathematically alongside summarizing.
09

Calculate Expected Gains

Determine overall expected value for each player based on their stakes: \(Profit = \frac {7}{5}\). Counters calculate consistency in the simulation.
10

Finalize Winner Profit

Include result breakdown, and finding C's value's relevant pays, accounting higher stake covers nor losses—insisting to still be profitable results in revised stakes compared here.

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Key Concepts

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

Outcome Calculation
Outcome calculation is a vital step in understanding dice probability problems. When dealing with dice, every roll can produce a finite number of results. Each die has 6 faces, numbered 1 through 6. When we roll two dice, we combine these results, leading to multiple possible outcomes. Here, we're interested in the total number of possibilities. For a single roll of two dice, we calculate the total outcomes by multiplying the number of faces on each die. Hence, if both players A and B roll one die each, we get: 6 (faces of die A) × 6 (faces of die B) = 36 possible outcomes.
After establishing the total outcomes, we must count the specific scenarios that fit our criteria—such as B's score being greater than A's score. By systematically working through the combinations, we identify 15 winning outcomes for B, considering all cases where A and B's dice rolls produce varied results. This understanding lays the groundwork for more advanced probability calculations and expected value assessments.
Probability Theory
Probability theory is the backbone of analyzing dice rolls. It helps us determine the likelihood of various events occurring, such as one gambler winning over another. The probability of an event is calculated as the ratio of the number of favorable outcomes to the total number of possible outcomes.
For instance, in the dice problem where B wins if his roll exceeds A's roll, the favorable outcomes for B winning are 15 out of 36 total outcomes. Hence, the probability of B winning is \(\frac{15}{36}\) or simplified to \(\frac{5}{12}\).
The odds are another way to express these probabilities. Odds represent the ratio of the number of favorable outcomes to the number of unfavorable outcomes. For A to win, we have calculated, from the step-by-step solution, the odds in A's favor as 7 to 5. This stems from comparing A’s wins and B’s wins: Probability(A’s win) = \(\frac{21}{36}\) (since neutral ties are removed in favor measurements) and Probability(B’s win) = \(\frac{15}{36}\). Adjusting these probabilities to ratio form gives us the winning odds for A as 7 to 5.
Expected Value
Expected value is a key concept that allows players to understand long-term outcomes in gambling scenarios. It represents the average result expected from repeated trials of a random event.
In problem (b), Gambler C's expected outcome when they both roll their dice twice needs analysis, especially with C increasing their stake to £1.10 while D continues with £1.00. To determine the expected value, the steps start with calculating the probabilities of each possible score sum from rolling two dice. These probabilities help in evaluating the chances of C's total score exceeding D's or vice versa.
For each possible total, we derive the probability by considering different combinations that produce the sum. We then use these probabilities to find the likelihood of one total being higher than another. Once the probabilities for all score scenarios are determined, we calculate the expected winnings for each player. The profit for C or D depends on the weighted average, factoring in stake adjustments. If C’s stake adjustment overcompensates for the odds' imbalance, we would conclude C to profit in the long run; otherwise, D would benefit.

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Most popular questions from this chapter

As assistant to a celebrated and imperious newspaper proprietor, you are given the job of running a lottery, in which each of his five million readers will have an equal independent chance, \(p\), of winning a million pounds; you have the job of choosing \(p\). However, if nobody wins it will be bad for publicity, whilst if more than two readers do so, the prize cost will more than offset the profit from extra circulation - in either case you will be sacked! Show that, however you choose \(p\), there is more than a \(40 \%\) chance you will soon be clearing your desk.

Show that, as the number of trials \(n\) becomes large but \(n p_{i}=\lambda_{i}, i=1,2, \ldots, k-1\), remains finite, the multinomial probability distribution (30.146), $$ M_{n}\left(x_{1}, x_{2}, \ldots, x_{k}\right)=\frac{n !}{x_{1} ! x_{2} ! \cdots x_{k} !} p_{1}^{x_{1}} p_{2}^{x_{2}} \cdots p_{k}^{x_{k}} $$ can be approximated by a multiple Poisson distribution with \(k-1\) factors: $$ M_{n}^{\prime}\left(x_{1}, x_{2}, \ldots, x_{k-1}\right)=\prod_{i=1}^{k-1} \frac{e^{-\lambda_{l}} \lambda_{i}^{x_{i}}}{x_{i} !} $$ (Write \(\sum_{i}^{k-1} p_{i}=\delta\) and express all terms involving subscript \(k\) in terms of \(n\) and \(\delta\), either exactly or approximately. You will need to use \(n ! \approx n^{\epsilon}[(n-\epsilon) !]\) and \((1-a / n)^{n} \approx e^{-a}\) for large \(\left.n .\right)\) (a) Verify that the terms of \(M_{n}^{\prime}\) when summed over all values of \(x_{1}, x_{2}, \ldots, x_{k-1}\) add up to unity. (b) If \(k=7\) and \(\lambda_{i}=9\) for all \(i=1,2, \ldots, 6\), estimate, using the appropriate Gaussian approximation, the chance that at least three of \(x_{1}, x_{2}, \ldots, x_{6}\) will be 15 or greater.

Show that, for large \(r\), the value at the maximum of the PDF for the gamma distribution of order \(r\) with parameter \(\lambda\) is approximately \(\lambda / \sqrt{2 \pi(r-1)}\).

In a certain parliament, the government consists of 75 New Socialites and the opposition consists of 25 Preservatives. Preservatives never change their mind, always voting against government policy without a second thought; New Socialites vote randomly, but with probability \(p\) that they will vote for their party leader's policies. Following a decision by the New Socialites' leader to drop certain manifesto commitments, \(N\) of his party decide to vote consistently with the opposition. The leader's advisors reluctantly admit that an election must be called if \(N\) is such that, at any vote on government policy, the chance of a simple majority in favour would be less than \(80 \%\). Given that \(p=0.8\), estimate the lowest value of \(N\) that would precipitate an election.

The duration (in minutes) of a telephone call made from a public call-box is a random variable \(T\). The probability density function of \(T\) is $$ f(t)= \begin{cases}0 & t<0 \\ \frac{1}{2} & 0 \leq t<1 \\ k e^{-2 t} & t \geq 1\end{cases} $$ where \(k\) is a constant. To pay for the call, 20 pence has to be inserted at the beginning, and a further 20 pence after each subsequent half-minute. Determine by how much the average cost of a call exceeds the cost of a call of average length charged at 40 pence per minute.

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