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Question
the total number of ways of forming groups by taking any number from n distinct objects is -
a) 2^n
b)2^n +1
c)2^n -1
d)none of these

I cant figure out whether to include nC0 0r not.

Answer
Hi Animesh,
We know the identity;
nC0 + nC1 + nC2 + ....... + nCn-1 + nCn = 2^n
Now, the total number of ways of forming groups by taking any number from n distinct objects is
nC1 + nC2 + ....... + nCn-1 + nCn   (we leave out nC0 since its an empty set)
= 2^n - nC0
= 2^n - 1

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