Tu znajdziesz drzewko do tego zadania
http://w519.wrzuta.pl/obraz/76qQE355EHK/drzewko_sohastyczne
a)
\frac{1}{12}*\frac{7}{11}*\frac{4}{10}
b)
\frac{4}{12}*\frac{1}{11}*\frac{3}{10}+\frac{4}{12}*\frac{1}{11}*\frac{4}{10}+
\frac{7}{12}*\frac{1}{11}*\frac{4}{10}+\frac{7}{12}*\frac{1}{11}*\frac{7}{10}
c)
\frac{4}{12}*\frac{3}{11}*\frac{7}{10}+\frac{4}{12}*\frac{7}{11}*\frac{6}{10}+
\frac{4}{12}*\frac{1}{11}*\frac{7}{10}+
+\frac{7}{12}*\frac{4}{11}*\frac{6}{10}+\frac{7}{12}*\frac{6}{11}*\frac{5}{10}
+\frac{7}{12}*\frac{1}{11}*\frac{7}{10}+
+\frac{1}{12}*\frac{4}{11}*\frac{7}{10}+\frac{1}{12}*\frac{7}{11}*\frac{6}{10}