The set S has 36 different subsets each of which contains exactly two elements.
The set S has 36 different subsets each of which contains exactly two elements. How many subsets of S could contain exactly four elements each?
Answer/Solution
126
Steps/Work
nC2 = 36
=> n*(n-1)/2 = 36 by middle term factor n can not be negative
=> n = 9
nC3 = 9C4 = 126
So, Answer is A.
=> n*(n-1)/2 = 36 by middle term factor n can not be negative
=> n = 9
nC3 = 9C4 = 126
So, Answer is A.