Question

I have a question. What will be the number of proper subsets of setA?
U={1,2,3,4,5,6,7,8,9,10}
A={1,3,5,7}
B={5,7,9,10}
C={1,7,10}

Answer 1

well, there are 2^4 = 16 total subsets of A, the reasoning being that each of the four elements is either in or not in the set, and so there are two possibilities for the "1", two possibilities for the "3", and so on, so when you multiply them you get 16 in all. Now, one and only one of these is an *improper* subset, namely the set {1,3,5,7}=A
so, we remove this set and there are 15 proper subsets.