Let \( X \) be a random variable having a probability density function \( f \in \{ f_0, f_1 \} \), where 
For testing the null hypothesis \( H_0 : f = f_0 \) against \( H_1 : f = f_1 \), based on a single observation on \( X \), the power of the most powerful test of size \( \alpha = 0.05 \) equals