Presentation on theme: "Permutations and Combinations"— Presentation transcript:
1Permutations and Combinations Solve Counting Problems Using Multiplication PrincipleSolve Counting Problems Using PermutationsSolve Counting Problems Using CombinationsSolve Counting Problems Using Permutations involving non distinct objects
2Multiplication Principle of Counting If a task consists of a sequence of choices in which there are p selections for the first choice, q selections for the second choice and r selections for the third choice and so on then the task of making these selections can be done in p∙q∙r∙……..
3QuestionThe fixed price dinner at a restaurant provides the following choices Appetizer: Soup or Salad Entrée: Chicken, Beef, Fish or Pork Dessert: Ice Cream or Cheesecake How many different meals can be ordered?
4PermutationA permutation is an ordered arrangement of r objects chosen from n objects
5Permutations: Distinct objects with repetition The number of ordered arrangements of r objects chosen from n objects in which the n objects are distinct and repetition is allowed is equal to nr. The symbol P(n,r) represents the number of ordered arrangements of r objects chosen from n distinct objects where r≤ n and repetition is not allowed.
6Permutations of r objects chosen from n distinct objects without repetition The number of arrangements of n objects using r ≤ n of them in whichThe n objects are distinctOnce an object is used it can not be used againOrder is importantIs given by the formula
7ExampleThe International Airline Transportation Association assigns three letter codes to represent airport locations. For example the airport code for Ft Lauderdale, Florida is FLL. Notice that repetition is allowed in forming this code. How many airport codes are possible?
8ExampleSuppose that we wish to establish a three letter code using any of the 26 uppercase letters of the alphabet, but we require that no letter be used more than once. How many different three letter codes are there?
9Lining up peopleIn how many ways can 5 people be lined up?
10Birthday problemAll we know about Shannon, Patrick and Ryan is that they have different birthdays. If we listed all the possible ways this could occur how many would there be? Assume there are 365 days in a year
11CombinationsA combination is an arrangement, without regard to order, of r objects selected from n distinct objects without repetition, where r ≤n. The symbol C(n,r) represents the number of combinations of n distinct objects using r of them.
12Forming CommitteesHow many different committees of 3 people can be formed from a pool of 7 people?
13Forming Committees 2In how many ways can a committee consisting of 2 faculty members and 3 students be formed if 6 faculty members and 10 students are eligible to serve on the committee?
14Forming different words How many different words (real or imaginary) can be formed using all the letters in the word REARRANGE?
15Number of combinations of n distinct objects taken r at a time The number of arrangements of n objects using r≤n of them, in whichTh n objects are distinctOnce an object is used, it cannot be repeatedOrder is not importantis given by the formula
16Permutations involving n objects that are not distinct The number of permutations of n objects of which n1 are of one kind and n2 are of a second kind…….and nk are of the kth kind is given by
17QuestionThe student relations committee of a college consists of 2 administrators 3 faculty members and 5 students. Four administrators, 8 faculty members, and 20 students are eligible to serve. How many different committees are possible?
18QuestionHow many different 9 letter words (real and imaginary) can be formed from the letters in the word ECONOMICS?
19QuestionHow many different 11 letter words (real or imaginary) can be formed from the letters in the word MATHEMATICS?