Oh! Got it! And if it wasn't half then how would you do the problem?

anonimnystefy

2013-03-27 22:07:50

No. If it is >=12, the complement's element sum is less than 55-12=43.

Agnishom

2013-03-27 22:03:22

Suppose it is some other number, say 12 Now for all sets whose sum is >=12 their compliments sum is <12 Therefore there are as many sets which sum more than or equal to 12 as the sets which sum less than 12 So....????

anonimnystefy

2013-03-27 22:00:22

Why is that?

Agnishom

2013-03-27 15:35:14

On second thoughts.... I doubt it

anonimnystefy

2013-03-27 04:10:21

You are welcome!

Agnishom

2013-03-27 03:54:51

I mean I understood TY

anonimnystefy

2013-03-27 03:39:15

What is it?

Agnishom

2013-03-27 02:58:06

Hmm...

anonimnystefy

2013-03-27 01:13:18

It is half because if a set's sum of elements is >=28, then the sum of elements of its complement is <28. That means that there are as many subsets of the given set which have the element sum >=28 as there are with the element sum <28.