JEE Main & Advanced JEE Main Paper (Held On 19 April 2014)

  • question_answer
    Two women and some men participated in a chess tournament in which every participant played two games with each of the other participants. If the number of games that the men played between themselves exceeds the number of games that the men played with the women by 66, then the number of men who participated in the tournament lies in the interval:     JEE Main Online Paper (Held On 19 April 2016)

    A) [8, 9]                     

    B) [10, 12)

    C) (11, 13]                                

    D) (14, 17)

    Correct Answer: B

    Solution :

    Let no. of men = n No. of women = 2 Total participants = n + 2 No. of games that\[{{M}_{1}}\]plays with all other men = 2(n ? 1) These games are played by all men \[{{M}_{2}},{{M}_{3}},\] ......, \[{{M}_{n}}.\] So, total no. of games among men = n.2(n ? 1). However, we must divide it by ?2?, since each game is counted twice (for both players). So, total no. of games among all men = n(n ? 1) ....... (1) Now, no. of games \[{{M}_{1}}\]plays with \[{{W}_{1}}\]and \[{{W}_{2}}=4\](2 games with each) Total no. of games that \[{{M}_{1}},{{M}_{2}},\] ....., \[{{M}_{n}}\] play with \[{{W}_{1}}\]and \[{{W}_{2}}=4n\]                                                .... (2) Given : \[n(n-1)-4n=66\]\[\Rightarrow \]\[n=11-6\] As the number of men can't be negative. So, n = 11


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