# How Many Permutations Of The Letters Abcdefgh Contain

How Many Permutations Of The Letters Abcdefgh Contain – Counting: Find the number of ways to select a given number of elements from a set Sometimes the order of these elements is important Example: In how many ways can we select 3 students from a group of 5 students? How many different ways do they line up for a picture?

3 Permutations In how many ways can we choose 3 students from a group of 5 to line up for the picture? First, note that the order in which we select students is important. There are 5 ways to choose the 1st student After the 1st student is chosen, there are 4 ways to choose the 2nd student in line. According to the product rule, there are 5x4x3=60 ways to select 3 students from a group of 5 students to line up for the picture.

## How Many Permutations Of The Letters Abcdefgh Contain

4 Permutations In how many ways can we arrange all 5 students in a row for the picture? According to the product rule, for 5x4x3x2x1=120 pictures, there are ways to place all 5 students in a row.

### Solved:how Many Bit Strings Of Length 10 Contain Either Five Consecutive 0 S Or Five Consecutive 1 \mathrm{s} ?

5 Permutation A permutation of a set of different objects is an ordered arrangement of these objects. An ordered arrangement of r elements of a set is called an r-permutation. , r). We can find P(n, r) using the product rule Example: Let S=. The arrangement 3, 1, 2 is a permutation of S. 3 is a 2-order permutation of S.

6 Let the permutation S= . 2-permutations of S are ordered arrangements, a, b; a, c; b, a; b, c; c, a; and c, b Consequently, this set has 6 2-permutations with 3 elements. Note that there are 3 ways to select item 1, then 2 ways to select item 2. By the product rule, P(3, 2) exists. =3 x 2 = 6

7 r-permutation theorem 1: If n is positive and r is an integer with 1≤r≤n, then P(n, r)=n(n-1)(n-2)…(n-r). +1) r-permutations of a set with n elements Proof: Use the product rule, the first element can be chosen in n ways. There are n-1 ways to select the 2nd element. Similarly, there are n-2 ways to select the 3rd element, until there are exactly n-(r-1)=n-r+1 ways to select the rth element. So the set has n∙(n-1)∙(n-2)… ∙(n-r+1) r-permutations.

8 r-permutation Note that p(n, 0)=1 when n is a non-negative integer because there is a way to sort the zero element. Corollary 1: If n and r are integers 0≤r≤n, then P(n) , r)=n!/(n-r)! Proof: If n and r are integers 1≤r≤n, then by Theorem 1 P(n, r)=n(n-1)…(n-r+1)=n!/(n-r) it happens! Since n!/(n-0)!=1 when n is a non-negative integer, we have P(n, r)=n!/(n-r)! When r=0, i.e. p(n, 0)=1

## Solved: In Studying The Uniformity Of Polysilicon Thickness On A Wafer In Semi

9 r-permutation By Theorem 1, we know that if n is a positive integer, then P(n, n)=n! P(n, n)=n!/(n-n)!=n! Example: How many ways are there to choose a 1st prize winner, a 2nd prize winner, and a 3rd prize winner from 100 different contestants? P(100, 3)=100x99x98=970, 200

10 Example How many permutations of the letters ABCDEFGH contain the string ABC? Since ABC must occur as a block, we can find the answer by locating the 6 letters, the ABC block, and the individual letters D, E, F, G, and H. Since these 6 objects must occur in any order, there are 6!=720 permutations of the letters ABCDEFGH in which ABC occurs in the block.

11 Combinations How many different committees of 3 students can be formed from a group of 4 students? We need to find the number of 3-element subsets from the set containing 4 students. We see that there are 4 such subsets, one for each of the 4 students, and selecting 4 students is the same as not selecting one of the 4 students. group This means that there are 4 ways to select 3 students for the committee, where the order in which these students are selected does not matter

12 r-combination An r-combination of the elements of a set is a random selection of r elements from the set. An r-combination is simply a subset of a set with r elements. Denote by C(n, r). Note that C(n, r) is also denoted by and is called the binomial coefficient

### Solved:how Many Permutations Are There Of The Letters In The Words (a) Triskaidekaphobia (fear Of The Number 13)? (b) Floccinaucinihilipilification (estimating Something As Worthless)? (c) Pneumonoultramicroscopicsilicovolcanoconiosis (a Lung Disease

13 Example Let S be a set. Then S is a 3-combination We see that C(4, 2)=6, because the 2-combination is 6 subsets , , , , , and

14 r-combinations Using the formula for the number of r-permutations of a set, we can determine the number of r-combinations of a set with n elements. and then ranks the elements in these combinations

15 r-combinations The number of r-combinations of a set with n elements, where n is a non-negative integer and r is an integer with 0≤r≤n. Proof: The r-permutations of a set can be obtained in the following form. C(n, r) r-combinations and then ordering the elements in each r-permutation which can be done by P(r, r) methods

17 Example How many poker hands of 5 cards can be dealt from a standard deck of 52 cards? Also, how many ways are there to choose 47 cards from a standard deck of 52 cards? Pick 5 out of 52 cards: C(52, 5)=52!/(5!47!)= (52x51x50x49x48)/(5x4x3x2x1)=26x17x10x49x12=2, 598, 960 C(52, 47) 47!5!) =2, 5, 98, 960

### Sample/practice Exam 2012, Questions

19 Combinatorial Proof A combinatorial proof of an identity is a proof that uses calculus arguments to prove that both sides of an identity count the same objects but in different ways. Proof of Corollary 2: Assume that S is a set with n elements. Every subset A of S with r elements corresponds to a subset S with n-r elements, that is, C(n, r)=C(n, n-r)

20 Example How many ways are there to select 5 players from a 10-person tennis team? Choose 5 out of 10 elements, i.e. C(10, 5)=10!/(5!5!)=252 How many bit strings of length n contain exactly r 1? This is equivalent to selecting r from n elements, i.e. C(n, r)

To operate this website, we collect user data and share it with processors. To use this website, you must agree to our Privacy Policy, including our cookie policy.2 Stimulating question How many ways are there to line up family members in a family of 3 for a photo? 3 x 3 3! 3 x 3 x 3 23

TSP: Given a list of cities and their pairwise distances, find the shortest tour that visits each city exactly once. Objective: d(i, j) Find the sequence of cities a1, …, a that minimizes the distance between cities i and j Optimal TSP tour of the 15 largest cities in Germany. This is the shortest possible tour, visiting each city once. Many computer science problems involve finding the best order of a collection of objects. These are called permutations. The optimal TSP tour of Germany’s 15 largest cities

## Answered: 6.5 Worksheet Exercise 6.5.3: Counting…

4 Permutations A permutation of a set of different objects is an ordered arrangement of these objects. Example: (1, 3, 4, 2) is the permutation of the numbers 1, 2, 3, 4. How many permutations of n objects are there?

6 Anagrams Anagram: a word, phrase, or name formed by rearranging the letters of another. Examples: “cinema” is an anagram of iceman “Tom Marvolo Riddle” is an anagram of “I am Lord Voldemort” Anagram server: Anagram games, e.g. Clabbers: tiles can be placed in any order on the board if they are anagrams to a valid word. Permutation City begins with a 20-line anagrammatic poem.

8 Example You invite 6 people for dinner. How many ways are there to seat them around the round table? (If everyone has the same left and right neighbors, consider the two seats to be the same). 6! 5! 7! You can express this as 6!/6 (the book calls this the division rule). Or say 5! From the start, because it doesn’t matter where you put the first one in a circle, there are 5 others to arrange.

9 Example Count the ways to line up n men and n women so that no two men are next to each other and no two women are next to each other. a) n! b) n! n! c) 2 n! n!

Go through all the changes of cities and estimate the sum of the distances keeping the optimal tour. (n-1)!/2 side note: Do we really need to consider all permutations of n cities?

How to create permutations recursively put all permutations of 1 first put 2 first put all permutations of 3 first.

Does it work? def perm(A, f):   if f == len(A)-1:     print(A)   else:     for i in range(f, len(A)) :       A[i], A[f] = A[ f ], A[i]       perm(A, f+1) A = []   for i in range(n):       A.append(i)     perm(A, 0) Let’s try

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