Permutation and Combination


  1. In how many ways, the letters of the word 'BANKING' can be arranged ?











  1. View Hint View Answer Discuss in Forum

    Total letters = 7, but N has come twice.
    So, required number of arrangements = 7 ! / 2 !

    Correct Option: D

    Total letters = 7, but N has come twice.
    So, required number of arrangements = 7 ! / 2 !
    = [7 x 6 x 5 x 4 x 3 x 2 ! ] / 2 ! = 2520


  1. In how many ways, the letters of the word 'STRESS' can be arranged ?











  1. View Hint View Answer Discuss in Forum

    Required number of arrangements = 6 ! / 3 ! [∵ S has come thrice ]

    Correct Option: D

    Required number of arrangements = 6 ! / 3 ! [∵ S has come thrice ]
    = [ 6 x 5 x 4 x 3! ] /3 !
    = 120



  1. In how many ways, the letters of the word 'ARMOUR' can be arranged ?











  1. View Hint View Answer Discuss in Forum

    Number of arrangements n ! /( p ! q ! r ! )
    Total letters = 6, but R has come twice.
    So, required number of arrangements
    = 6 ! / 2 !

    Correct Option: E

    Number of arrangements n ! /( p ! q ! r ! )
    Total letters = 6, but R has come twice.
    So, required number of arrangements
    = 6 ! / 2 ! = (6 x 5 x 4 x 3 x 2 !) / 2 ! = 360


  1. In how many different ways, can the letters of the word 'INHALE' be arranged ?











  1. View Hint View Answer Discuss in Forum

    The word 'INHALE' has 6 distinct letters.
    ∴ Number of arrangements = n !

    Correct Option: A

    The word 'INHALE' has 6 distinct letters.
    ∴ Number of arrangements = n ! = 6 !
    = 6 x 5 x 4 x 3 x 2 x 1
    = 720



  1. If 56Pr + 6 : 54Pr + 3 = 30800 : 1 then the value of r is ?









  1. View Hint View Answer Discuss in Forum

    56Pr + 6 : 54Pr + 3 = 30800 : 1
    ⇒ 56! / (50 - r)! = (30800 x 54!) / (51-r!)

    Correct Option: B

    56Pr + 6 : 54Pr + 3 = 30800 : 1
    ⇒ 56! / (50 - r)! = (30800 x 54!) / (51-r!)
    ⇒ 56 x 55 = 30800/(51 - r)
    ⇒ 51 - r = 10
    ∴ r = 41