Lecture 3 Chapter 7 Class 11 Maths

“Everything you’ve ever wanted is on the other side of fear.” — George Addair

Lecture - 3 Chapter 7 Permutations and Combinations

Number of Permutations when an alphabet repeat

Example 14. Find the number of different 8-letter arrangements that can be made from the letters of the word DAUGHTER so that
(i) all vowels occur together
(ii) all vowels do not occur together.

Example 16. Find the number of arrangements of the letters of the word INDEPENDENCE. In how many of these arrangements,
(i) do the words start with P
(ii) do all the vowels always occur together
(iii) do the vowels never occur together
(iv) do the words begin with I and end in P?

NCERT Exercise 7.3

Question 10. In how many of the distinct permutations of the letters in MISSISSIPPI do the four I’s not come together?

Question 11. In how many ways can the letters of the word PERMUTATIONS be arranged if the
(i) words start with P and end with S,
(ii) vowels are all together,
(iii) there are always 4 letters between P and S?