In a chess tournament every person played one game with every other pe...
MC2 - MC1 wC1 = 18, where M and W are the number of men and women respectively.
View all questions of this test
In a chess tournament every person played one game with every other pe...
Problem Analysis:
We are given that every person played one game with every other person in the group. We need to find the total number of games played in the tournament when the total number of games that men played between themselves exceeded those played by men with women by 18.
Given:
- Total number of women in the tournament = 4
To find:
- The total number of games played in the tournament
Solution:
Let's assume there are 'n' people in the tournament.
- The number of games played by each person = (n-1)
- Total number of games played in the tournament = nC2 (combination of 'n' people taken 2 at a time)
As per the given condition, the total number of games that men played between themselves exceeded those played by men with women by 18.
Let's assume the number of men in the tournament = 'm'. Then the number of women in the tournament = (n-m).
- Number of games played between men = mC2
- Number of games played between men and women = m*(n-m)
- Given, mC2 - m*(n-m) = 18
Simplifying the above expression, we get:
mC2 - m*n + m^2 + 18 = 0
mC2 = (nC2 - m*n) + 18
Substituting the value of nC2 in terms of 'n':
mC2 = (n*(n-1)/2 - m*n) + 18
2mC2 = n*(n-1) - 2m*n + 36
2mC2 = n*(n-2m+1) + 36
As per the given condition, there are 4 women in the tournament.
Hence, the number of men = n-4
Substituting this value in the above equation, we get:
2(mC2) = (n-4)*(n-2m+5) + 36
We know that the total number of games played in the tournament = nC2
Substituting the value of nC2 in terms of 'n':
2(mC2) = n*(n-1) - 4*(n-4) - 2m*n + 10m + 36
2(mC2) = n^2 - 2mn + 10m - 4
n^2 - 2mn + 10m - 4 - 2(mC2) = 0
We can solve this equation to get the value of 'n'.
n = [2m + sqrt(4m^2 - 40m + 36 + 8mC2)] / 2
n = m + sqrt(m^2 - 10m + 9 + 2mC2)
We know that 'n' is an integer, hence we need to find the value of 'm' such that the above expression gives an integer value for 'n'.
As 'm' increases, the value of 'n' also increases. We can try different values of 'm' to find the smallest possible value of 'm' that gives an integer value for 'n'.
Trying different values of 'm', we get:
- For m = 10, n = 20
- For m = 11, n =