Logo
    Logo

    Subject

    Quantitative Aptitude

    Topic

    Permutation & Combination

    The number of ways in which 20 different flowers of two colors can be set alternately on a necklace, there being 10 flowers of each colour, is

    ক)
    9! × 10!
    খ)
    5(9!)2
    গ)
    (9!)2
    ঘ)
    (18!)2
    ঙ)
    None of these

    Explanation

    First of all we will make circular permutations for all the flowers of a particular colour. We know that, for permutation of n objects in a circle is = (n - 1)! So, for 10 flowers of same colour, the permutations in 10 places = (10 - 1)! = 9! Now, for permutation of the remaining ten flowers of same colour in between the previously placed flowers = 10! Now, since this is a necklace hence the number of permutations are divided by 2. Hence, the required answer = (9! × 10!)/2 = 5(9!) 2

    Related questions

    At a party, everyone shook hands with everyone else, If there were 66 handshakes, how many people were at the party?At a party, everyone must shake the hand of the other. If the total number of handshakes Is 66, there are ____ people at the party.There are 3 doors to a lecture room. In how many ways can a lecturer enter and leave the room?At a party, everyone shook hands with everybody else. If there were 66 handshakes, how many people were at the party?In how many different ways can the letters of the word 'OPTICAL' be arranged so that the vowels always come together?In how many different ways can the letters of the word 'MATHEMATICS' be arranged so that the vowels always come together?How many 4-letter words with or without meaning, can be formed out of the letters of the word, 'LOGARITHMS', if repetition of letters is not allowed?In how many ways can a group of 5 men and 2 women be made out of a total of 7 men and 3 women?

    Find Tutors

    View all Tutors