LINKING
concepts... For Individual or Group Explorations
Using Matrices to Rank Teams
The table on the next page gives the records of all four teams in a soccer league. An entry of I indicates that the row team has defeated the column team. (There are no ties.) The teams are ranked, not by their percentage of victories, but by the number of points received under a ranking scheme that gives a team credit for the quality of the team it defeats. Since team A defeated B and C. A gels two points. Since B defeated C and D, and C defeated D, A gels 3 more secondarypoints for a total of 5 points.
(continued)
Since D's only victory is over A, D gels 1 point for that victory plus 2 secondary points for A‘s defeats of H and C. giving D a total of 3 points.
a) Write the table as a 4 X 4 matrix M and find M2.
b) Explain what the entries of M2 represent.
c) Now let T be a 4 X 1 matrix with a I in every entry. Find (M + M2)T.
d) Explain what the entries of (M + M2)T represent.
e) Is it possible for one team to have a better win-loss record than another, but end up ranked lower than the other because of this point scheme? Give an example to support your answer.
f) Make up a win-loss table (with no ties) for a six-team soccer league like the given table. Use a graphing calculator to find (M + M2)T. Compare the percentage of games won by each team with its ranking by this scheme. Is it possible for a team to have a higher percentage of wins but still be ranked lower than another team?
g) Find (2M + M2)T for the matrix M from part (0 and explain its entries. What is the significance of the number 2?
h) Compare the ranking of the six teams using (2M + M2)T and (M + M2)T. Is it possible that (2M + M2)T could change the order of the teams?
A |
B |
c |
D |
|
A |
0 |
1 |
1 |
0 |
B |
0 |
0 |
1 |
1 |
c |
0 |
0 |
0 |
1 |
D |
1 |
0 |
0 |
0 |
Want to see the full answer?
Check out a sample textbook solutionChapter 6 Solutions
College Algebra (6th Edition)
- A factory manufactures three products (doohickies, gizmos, and widgets) and ships them to two warehouses for storage. The number of units of each product shipped to each warehouse is given by the matrix A=[20015010075100125] (where aij is the number of units of product i sent to warehouse j and the products are taken in alphabetical order). The cost of shipping one unit of each product by truck is $1.50 per doohickey, $1.00 per gizmo, and $2.00 per widget. The corresponding unit costs to ship by train are $1.75, $1.50, and $1.00. Organize these costs into a matrix B and then use matrix multiplication to show how the factory can compare the cost of shipping its products to each of the two warehouses by truck and by train.arrow_forwardLet A and B be square matrices of order 4 such that |A|=5 and |B|=3.Find a |A2|, b |B2|, c |A3|, and d |B4|arrow_forwardDetermine the dimension of the matrix 14710238.arrow_forward
- Consider the matrix A=[2314]. Show that any of the three types of elementary row operations can be used to create a leading 1 at the top of the first column. Which do you prefer and why?arrow_forwardDetermine whether the matrix is in row-echelon form. If it is, determine whether it is in reduced row-echelon form. 1024011130000arrow_forwardGive examples of matrices A and B of the same size such that (a) rank(A+B)rank(A) and rank(A+B)rank(B) (b) rank(A+B)=rank(A) and rank(A+B)=rank(B) (c) rank(A+B)rank(A) and rank(A+B)rank(B).arrow_forward
- Linear Algebra: A Modern IntroductionAlgebraISBN:9781285463247Author:David PoolePublisher:Cengage LearningCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage LearningAlgebra & Trigonometry with Analytic GeometryAlgebraISBN:9781133382119Author:SwokowskiPublisher:Cengage
- College AlgebraAlgebraISBN:9781305115545Author:James Stewart, Lothar Redlin, Saleem WatsonPublisher:Cengage LearningElementary Linear Algebra (MindTap Course List)AlgebraISBN:9781305658004Author:Ron LarsonPublisher:Cengage Learning