An Open e-Library for Engineering Entrance Exams in India.
permutations&combinations
  • find the number of 3 digit numbers,whose middle digit is bigger than extreme digits
  • 4 Comments sorted by
  • well.....that was a good question indeed...

    answer is 240

    Explanation:

    least value of middle number: 2

    Units digit can have 2 possible values (0,1)
    and the 100th digit can have 1 possible value (1) therefore, numbers possible is 1X2


    When, middle number's value is 3. Units digit can have 3 possible values (0,1,2) and the 100th digit can have 2 possible values (1,2) therefore, numbers possible is 2X3

    And so on....(units digit value could be 2....9)

    Hence, total no. of possible numbers are: 1X2 + 2X3 + .........+ 7X8 + 8X9 = 240

    howzthat?!!

    Karma me +1 if im correct!! :-)
  • the no of triangles that can be formedby 5 points in a line and 3 points on a parallel line
  • 8C3-5C3-3C3
    ....???
  • i think viniket is rite!!

Howdy, Stranger!

It looks like you're new here. If you want to ask questions, login using your Google or Facebok IDs!

Login with Facebook Sign In with Google Sign In with OpenID Sign In with Twitter

In this Discussion

This is a beta version of the new KnowledgeBin.org. Please provide your feedback here: http://bit.ly/knowledgebin

Share Me

  • Please share this topic with your friends. Click any of the icons below:
  • stumbleupon
  • Twitter
  • facebook
  • myspace
  • technorati
  • reddit
  • fark
  • email

Top Posters