Math  /  Data & Statistics

Question2. Refer to the following preference schedule to answer parts (a) - (f). Note: See attached page for additional copies of the table. ( 36pts436 \mathrm{pts}-4 pts for each part) \begin{tabular}{|r|c|c|c|c|} \hline First & A & B & D & C \\ \hline Second & B & D & C & B \\ \hline Third & C & A & B & A \\ \hline Forth & D & C & A & D \\ \hline Number of Voters & 30 & 20 & 25 & 10 \\ \hline \end{tabular} a. How many votes were cast? \qquad b. How many votes are needed to receive a majority? \qquad c. Find the plurality winner: \qquad d. Did the plurality winner also receive a majority? \qquad Show work to support the selection process below. e. Find the winner by a single runoff of the top two candidates: \qquad Show work to support the selection process below. f. Find the winner by a sequential runoff: \qquad Show work to support the selection process below. g. Find the winner by a Borda count: \qquad Show work to support the selection process below. h. Find the winner, if any, by the method of pairwise comparisons: \qquad Show work to support the selection process below.

Studdy Solution

STEP 1

1. The preference schedule is given as a table with candidates A, B, C, and D.
2. The number of voters for each preference order is provided.
3. The tasks involve determining winners using different voting methods.

STEP 2

1. Calculate the total number of votes cast.
2. Determine the number of votes needed for a majority.
3. Identify the plurality winner.
4. Check if the plurality winner also received a majority.
5. Determine the winner by a single runoff of the top two candidates.
6. Determine the winner by a sequential runoff.
7. Determine the winner by a Borda count.
8. Determine the winner by the method of pairwise comparisons.

STEP 3

Calculate the total number of votes cast by summing the number of voters for each preference order:
30+20+25+10=85 30 + 20 + 25 + 10 = 85

STEP 4

Calculate the number of votes needed to receive a majority. A majority is more than half of the total votes:
Majority=852=42.5 \text{Majority} = \frac{85}{2} = 42.5
Since a candidate cannot receive a fraction of a vote, round up to the next whole number:
43 43

STEP 5

Identify the plurality winner by finding the candidate with the most first-place votes:
- A: 30 votes - B: 20 votes - D: 25 votes - C: 10 votes
The plurality winner is candidate A with 30 votes.

STEP 6

Check if the plurality winner (A) also received a majority:
Candidate A received 30 votes, which is less than the majority of 43 votes.

STEP 7

Determine the winner by a single runoff of the top two candidates (A and D):
- A: 30 votes - D: 25 votes
In a runoff, consider the second preferences of voters who did not vote for A or D initially:
- 20 voters prefer B first, then D - 10 voters prefer C first, then B
Redistribute these votes:
- A: 30 votes - D: 25 + 20 = 45 votes
The winner by a single runoff is candidate D.

STEP 8

Determine the winner by a sequential runoff:
1. Eliminate the candidate with the fewest first-place votes (C with 10 votes).
2. Redistribute C's votes based on second preferences (to B).
3. New totals: A: 30, B: 20 + 10 = 30, D: 25
4. Eliminate B (tied with A but fewer initial votes).
5. Redistribute B's votes based on second preferences (to D).
6. New totals: A: 30, D: 25 + 20 = 45

The winner by a sequential runoff is candidate D.

STEP 9

Determine the winner by a Borda count:
Assign points based on rank (3 for first, 2 for second, 1 for third, 0 for fourth):
- A: 30×3+20×2+25×1+10×0=90+40+25+0=15530 \times 3 + 20 \times 2 + 25 \times 1 + 10 \times 0 = 90 + 40 + 25 + 0 = 155 - B: 30×2+20×0+25×1+10×3=60+0+25+30=11530 \times 2 + 20 \times 0 + 25 \times 1 + 10 \times 3 = 60 + 0 + 25 + 30 = 115 - C: 30×1+20×3+25×0+10×2=30+60+0+20=11030 \times 1 + 20 \times 3 + 25 \times 0 + 10 \times 2 = 30 + 60 + 0 + 20 = 110 - D: 30×0+20×1+25×3+10×1=0+20+75+10=10530 \times 0 + 20 \times 1 + 25 \times 3 + 10 \times 1 = 0 + 20 + 75 + 10 = 105
The winner by Borda count is candidate A.

STEP 10

Determine the winner by the method of pairwise comparisons:
Compare each pair of candidates:
- A vs. B: A wins (30 vs. 20) - A vs. C: A wins (30 vs. 10) - A vs. D: D wins (45 vs. 30) - B vs. C: B wins (20 vs. 10) - B vs. D: D wins (45 vs. 20) - C vs. D: D wins (45 vs. 10)
D wins the most pairwise comparisons.
The winner by the method of pairwise comparisons is candidate D.

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