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\begin{array}{rclll} 0{,}2 &=& \dfrac{5^{x-1}}{10} &\vert & \cdot 10 \cr 2 &=& 5^{x-1} &\vert & \ln{()} \cr \ln{(2)} &=& \ln{\left(5^{x-1}\right)}\cr \ln{(2)} &=& (x-1) \cdot \ln{(5)} &\vert & :\ln{(5)}\cr \dfrac{\ln{(2)}}{\ln{(5)}} &=& x-1 &\vert & +1 \cr \dfrac{\ln{(2)}}{\ln{(5)}}+1 &=& x \cr x &\approx& 1{,}43 \in\mathbb{D} & & \rightarrow \quad P_2(1{,}43 \mid 0{,}2) \end{array}