③) 1) 1½ · ½ = ? 2) 2¾ · ⅗ = ? 3) 3 · ⅕ = ? 4) 5/16 · 3 = ?

Решение:

1. 1) \( 1\frac{1}{2} \cdot \frac{1}{2} = \frac{3}{2} \cdot \frac{1}{2} = \frac{3}{4} \)
2. 2) \( 2\frac{3}{4} \cdot \frac{3}{5} = \frac{11}{4} \cdot \frac{3}{5} = \frac{33}{20} = 1\frac{13}{20} \)
3. 3) \( 3 \cdot \frac{1}{5} = \frac{3}{1} \cdot \frac{1}{5} = \frac{3}{5} \)
4. 4) \( \frac{5}{16} \cdot 3 = \frac{5}{16} \cdot \frac{3}{1} = \frac{15}{16} \)

Ответ: 1) \(\frac{3}{4}\); 2) \(1\frac{13}{20}\); 3) \(\frac{3}{5}\); 4) \(\frac{15}{16}\).