is a set containing elements. A subset of is chosen. The set is reconstructed by replacing the elements of . A subset of is again chosen. The number of ways of choosing and so that is?
The explanation for the correct option:
Step 1. Let For each we have the following four cases
Step 2. For (i), (ii) and (iii),
Thus, the total number of ways of choosing and is
Out of these four choices, (i) is not favorable for
Thus, the number of ways
Hence, the correct option is option (D).