Let E and F be two events such that P ( E )=0 · 1, P ( F )=0 · 3, P ( E ∪ F )=0 · 4, then P ( F ∣ E ) is:

Let E and F be two events such that $\displaystyle \mathrm{P}(\mathrm{E})=0 \cdot 1, \mathrm{P}(\mathrm{F})=0 \cdot 3, \mathrm{P}(\mathrm{E} \cup \mathrm{F})=0 \cdot 4$, then $\displaystyle \mathrm{P}(\mathrm{F} \mid \mathrm{E})$ is :