Last updated at May 29, 2018 by Teachoo

Transcript

Example 16 Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements, Finding total number of arrangements In word INDEPENDENCE There are 3N, 4E, & 2D, 1I, 1P & 1C Since letters are repeating so we use this formula ! 1! 2! 3! Total letters = 12 So, n = 12 Since, 3N, 4E, & 2D p1 = 3, p2 = 4,p3 = 2 Total arrangements = 12! 3!4!2! = 1663200 Example 16 Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements, do the words start with P If the word start with P We need to arrange (12 1) = 11 We need to arrange letters I,N,D,E,E,N,D,E,N,C,E Here, 4E, 3N,2D Since letters are repeating since we use this formula Number of arrangements = ! 1! 2! 3! Total letters to arrange = 11 So, n = 11 Since, 4E, 3N,2D p1 = 4 , p2 = 3 , p3 = 2 Number of arrangements = ! 1! 2! 3! = 11! 4!3!2! = 138600 Example 16 Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements, do the words start with P If the word start with P We need to arrange (12 1) = 11 We need to arrange letters I,N,D,E,E,N,D,E,N,C,E Here, 4E, 3N,2D Since letters are repeating since we use this formula Number of arrangements = !/ 1! 2! 3! Total letters to arrange = 11 So, n = 11 Since, 4E, 3N,2D p1 = 4 , p2 = 3 , p3 = 2 Number of arrangements = !/ 1! 2! 3! = 11!/4!3!2! = 138600 Example 16 Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements, (ii) do all the vowels always occur together There are 5 vowels in the given word INDEPENDENCE i.e. 4E s & I s They have occur together we treat them as single object we treat as a single object So our letters become We arrange them now Hence the required number of arrangement = 8!/3!2! 5!/4! = ((8 7 6 5 4 3!) (5 4!))/(3! 4! 2) = 16800 Example 16 Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements, (iii) do the vowels never occur together Number of arrangements where vowel never occur together = Total number of arrangement Number of arrangements when all the vowels occur together = 1663200 16800 = 1646400 Example 16 Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements, (iv) do the words begin with I and end in P? Lets fix I and P at Extreme ends Since letters are repeating, Hence we using this formula !/ 1! 2! 3! Here Total letters = n = 10 Since 2D, 4E, 3N p1 = 2, p2 = 4, p3 = 3 Required number of arrangement = 10!/2!4!3! = 12600

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

Example 9

Example 10

Example 11

Example 12

Example 13 Important

Example 14

Example 15

Example 16 Important You are here

Example 17

Example 18

Example 19 Important

Example 20

Example 21

Example 22

Example 23 Important

Example 24

Chapter 7 Class 11 Permutations and Combinations

Serial order wise

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.