/*! 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 28 Presidential election. Two candi... [FREE SOLUTION] | 91Ó°ÊÓ

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Presidential election. Two candidates are running for president. Candidate \(A\) has already received \(80 \mathrm{elec}-\) toral votes and only needs 35 more to win. Candidate \(B\) already has 50 votes, and needs 65 more to win. Five states remain to be counted. Winning a state gives a candidate 20 votes; losing gives the candidate zero votes. Assume both candidates otherwise have equal chances to win in those five states. (a) Write an expression for \(W_{A}\), total, the number of ways A can succeed at winning 40 more electoral votes. (b) Write the corresponding expression for \(W_{B, \text { total. }}\). (c) What is the probability candidate \(A\) beats candidate \(B\) ?

Short Answer

Expert verified
Candidate A has a 13/16 chance of beating candidate B.

Step by step solution

01

- Understand the Problem

Candidate A needs 35 more votes to win, and Candidate B needs 65 more votes. Each remaining state gives 20 votes, and there are 5 states left. Both candidates have equal chances to win each state.
02

- Calculate Number of States A Needs

Candidate A needs at least 2 states to get at least 40 more votes (since each state provides 20 votes).
03

- Calculate Number of States B Needs

Candidate B needs at least 4 states to get at least 80 more votes (since each state provides 20 votes).
04

- Binomial Coefficient for A

To calculate the total number of ways A can win 2 or more states out of 5, use the combination formula: \[W_A = \binom{5}{2} + \binom{5}{3} + \binom{5}{4} + \binom{5}{5}\]
05

- Binomial Coefficient for B

To calculate the total number of ways B can win 4 or more states out of 5, use the combination formula: \[W_B = \binom{5}{4} + \binom{5}{5}\]
06

- Calculate Total Winning Possibilities

Calculate the values from the binomial coefficients: - For A: \(\binom{5}{2} = 10, \binom{5}{3} = 10, \binom{5}{4} = 5, \binom{5}{5} = 1\) \[W_A = 10 + 10 + 5 + 1 = 26\] - For B: \(\binom{5}{4} = 5, \binom{5}{5} = 1\)\[W_B = 5 + 1 = 6\]
07

- Calculate Probability A Beats B

The probability that A beats B is given by the ratio of the number of successful outcomes for A to the total number of possible outcomes (since both have equal chances): \[P(A \text{ beats } B) = \frac{W_A}{W_A + W_B}\] Therefore, \[P(A \text{ beats } B) = \frac{26}{26 + 6} = \frac{26}{32} = \frac{13}{16}\]

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Key Concepts

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

binomial coefficient
The binomial coefficient is crucial in probability theory. It’s used to determine the number of ways to choose a subset of items from a larger set. The formula for a binomial coefficient is given by: \( \binom{n}{k} = \frac{n!}{k!(n-k)!} \). In our presidential election problem, we use the binomial coefficient to determine the number of ways candidate A or B can win a certain number of states out of the five remaining. For example, Candidate A needs to win at least 2 states to get at least 40 additional electoral votes. So, we calculate: \( \binom{5}{2} + \binom{5}{3} + \binom{5}{4} + \binom{5}{5} \). Each term in this expression represents the different possible combinations of states that Candidate A can win.
probability calculation
Probability calculation is about finding the likelihood of a given event happening. In our scenario, we are interested in the probability that Candidate A will win the presidential election. We start by calculating the total number of successful ways each candidate can win the required states using binomial coefficients. Then, we use these values to find the probability: \( P(A \text{ beats } B) = \frac{W_A}{W_A + W_B} \). Here, \( W_A \) and \( W_B \) are the total successful outcomes for Candidates A and B respectively. Finally, substituting the values we found: \( P(A \text{ beats } B) = \frac{26}{26 + 6} = \frac{26}{32} = \frac{13}{16} \). This shows that Candidate A has a higher probability of winning over Candidate B.
combinatorial analysis
Combinatorial analysis involves counting and arranging items to solve probability problems. In our election problem, we count the number of ways each candidate can win the required number of states. This is where the binomial coefficients come into play. We calculate the combinations for Candidate A winning 2 or more states and Candidate B winning 4 or more states. By adding these combinations, we understand the possible outcomes. This combinatorial analysis helps us accurately determine how likely it is for each candidate to win, factoring in the different ways they can achieve the needed electoral votes.
statistical methods
Statistical methods are techniques used to collect, analyze, interpret, and present data. In our context, we use statistical methods to interpret the election problem and calculate probabilities. By understanding and utilizing binomial coefficients, as well as probability calculations, we extrapolate the likelihood of Candidate A or B winning. This involves interpreting combinatorial results and converting them to probabilities. The entire process provides a clear, numeric answer to the problem, demonstrating how statistical methods help in decision-making processes, especially in probabilities and elections.

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