Question:
If $A=\phi$ then find $n\{P(A)\}$
Solution:
We have, $A=\phi$, i.e. $A$ is a : set.
Then, $n(A)=0$
$\therefore \mathrm{n}\{\mathrm{P}(\mathrm{A})\}=2^{\mathrm{m}}$, where $\mathrm{m}=\mathrm{n}(\mathrm{A})$
$\Rightarrow \mathrm{n}\{\mathrm{P}(\mathrm{A})\}=2^{0}=1$.
Thus, $P(A)$ has one element.