Математика · 10 класс Задача №3242915
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1/2 2/15 6/21 \[ \frac{\binom{4}{2}}{\binom{7}{2}} = \frac{6}{21} \] \[ \frac{5}{36} + \frac{10}{36} = \frac{15}{36} = \frac{5}{12} \] \[ \frac{\binom{7}{3}}{\binom{10}{3}} = \frac{35}{120} = \frac{7}{24} \] \[ \frac{4}{31} \] \[ \frac{7}{20} \] \[ 0.45 + 0.35 = 0.8 \]