11. 2 7/8 * 1,2.

$$ 2 \frac{7}{8} \cdot 1,2 = \frac{23}{8} \cdot \frac{12}{10} = \frac{23}{2 \cdot 4} \cdot \frac{3 \cdot 4}{5 \cdot 2} = \frac{23 \cdot 3}{2 \cdot 5 \cdot 2} = \frac{69}{20} = 3 \frac{9}{20} $$

Ответ: $$3 \frac{9}{20} $$