Combinatorics Lesson 10 Principle of Mutual Exclusion and Inclusion

This video explains the principle of Mutual inclusion and exclusion along with the related problems.

Questions

  • 0

    What is floor and ceil value??

    Lakshman
    Reply

    Please explain more about ceil and floor.

  • 0

    What is relatively prime number and Non relatively prime number??

    Lakshman
    Reply

    please explain more about these question

  • 1

    Shouldn't 1 be also excluded?

    vishwajit_vishnu
    Reply

    1000 -734 removes the common multiples of 2,3,5 but it doesn’t remove 1 which is also non relatively prime with 30.

    • vishwajit_vishnu

      I got it that 1 is relatively prime with every natural no. My doubt is cleared

  • 1

    on divisibility problem

    kaustavpro19
    Reply

    so, In divisibility problem of principle of mutual of exclusion and inclusion,it is better to apply LCM of the factors.Am I correct?

  • 3

    the number between 1-1000 which are relatively prime to 80

    kabbupro19
    Reply

    the number between 1-1000 which are relatively prime to 80

    • getgatebook

      prime factors of 80 are 2,5.
      Now find all the numbers between 1-80 which are divisible by either 2 or 5 ?
      These are non relatively prime numbers of 80 in between 1-80.
      Now remove them from 80 and you get relatively prime numbers.

    • prashantpro

      @Sir Plz correct me if am wrong.

      But i think as per the question we have to find all the numbers between 1-1000 which are divisible by either 2 or 3(Using Union of sets formula).Then subtract the non relative prime numbers from 1000.

    • getgatebook

      Yes.