If the raining season in Jerusalem begins, Dora estimates a 20% probab

Yes, ss13ny , your solution is correct! Thanks for joining!

The official solution follows:

\(? = P\left( {{\rm{Dora}}\,\,{\rm{travels}}} \right)\)

\(P\left( {{\text{season}}\,\,{\text{raining}}} \right) = 70\% \,\,\,\,\,\, \Rightarrow \,\,\,\,\,P\left( {{\text{not}}\,\,{\text{season}}\,\,{\text{raining}}} \right) = 30\%\)

\(20\% \,\,\mathop \to \limits^{\, + \,250\% } \,\,\,\underbrace {60\% + 10\% }_{300\% \,\left( {20\% } \right)\, + \,50\% \left( {20\% } \right)} = 70\% \,\,\,\,\,\, \Rightarrow \,\,\,\,\,\left\{ \matrix{\\
P\left( {{\rm{travel}}\,\,{\rm{when}}\,\,{\rm{season}}\,\,{\rm{raining}}} \right) = 20\% \hfill \cr \\
P\left( {{\rm{travel}}\,\,{\rm{when}}\,\,{\rm{not \,\,season}}\,\,{\rm{raining}}} \right) = 70\% \hfill \cr} \right.\,\,\)


\(?\,\, = \,\,70\% \cdot 20\% + 30\% \cdot 70\% \,\, = \,\,\underleftrightarrow {70\% \cdot \left( {20\% + 30\% } \right)}\,\, = \,\,\frac{1}{2}\left( {70\% } \right)\,\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,\,\left( {\text{C}} \right)\)


We follow the notations and rationale taught in the GMATH method.

Regards,
Fabio.