The probability of the union of events E and F is calculated using the formula:
\[P(E \cup F) = P(E) + P(F) - P(E \cap F).\]
Given the values, we substitute them into the equation:
\[0.4 = 0.1 + 0.3 - P(E \cap F) \quad \Rightarrow \quad P(E \cap F) = 0.\]
The conditional probability of F given E is then determined by:
\[P(F \,|\, E) = \frac{P(E \cap F)}{P(E)} = \frac{0}{0.1} = 0.\]
Final Answer: \( \boxed{0} \)