\[\boxed{\mathbf{Проверочная\ работа\ №4.\ Проценты}}\]
\[\boxed{\text{1.}}\]
\[1\ :100 \cdot 2 = 0,01 \cdot 2 = 0,02.\ \ \ \]
\[\boxed{\text{2.}}\]
\[0,5\ :100 \cdot 5 = 0,005 \cdot 5 = 0,025.\ \ \ \]
\[\boxed{\text{3.}}\]
\[9\ :3 \cdot 100 = 3 \cdot 100 = 300.\ \ \ \]
\[\boxed{\text{4.}}\]
\[80\ :40 \cdot 100 = 2 \cdot 100 = 200.\ \ \ \]
\[\boxed{\text{5.}}\]
\[200\ :100 \cdot 0,2 = 2 \cdot 0,2 = 0,4.\ \ \ \]
\[\boxed{\text{6.}}\]
\[Нет.\]
\[После\ повышения\ цены\ товар\ \]
\[стал\ стоить:\ \]
\[300 + 300\ :100 \cdot 50 =\]
\[= 300 + 150 = 450\ (руб)\text{.\ \ \ }\]
\[\boxed{\text{7.}}\]
\[Да.\]
\[20\ кг\ от\ 1\ т = 1\ 000\ кг:\ \]
\[\frac{20}{1\ 000} \cdot 100\% = \frac{1}{50} \cdot 100\% =\]
\[= 2\%.\ \ \ \]
\[\boxed{\text{8.}}\]
\[Нет.\]
\[120\ \%\ от\ 1\ 200:\ \]
\[1\ 200\ :100 \cdot 120 = 12 \cdot 120 =\]
\[= 1\ 440.\]