2 members of a club are to be selected to represent the club at a national meeting. if there are 190 different possible selections of 2 members, how many members does the club have?
please explain
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190 selections of "n" members taken 2 at a time...
Which means nC2 = 190
n! /(n-2)! * 2! = 190
n*n-1*n-2!/n-2!*2=190
n*n-1=380
Therefore n=20
Which means nC2 = 190
n! /(n-2)! * 2! = 190
n*n-1*n-2!/n-2!*2=190
n*n-1=380
Therefore n=20
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Letting n = the number of members in the club, we have:yvonne12 wrote:2 members of a club are to be selected to represent the club at a national meeting. if there are 190 different possible selections of 2 members, how many members does the club have?
nC2 = 190
n(n - 1)/2 = 190
n^2 - n = 380
n^2 - n - 380 = 0
(n - 20)(n + 19) = 0
n = 20 or n = -19
Since the number of members can't be negative, n = 20.
Answer: 20
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