Question

scale factor:

Explanation:

Step1: Measure side - length of original and new rectangle

Let's assume we measure the horizontal side - length of rectangle $QRST$ and $Q'R'S'T'$. For example, if we measure the horizontal side of rectangle $QRST$ from $Q$ to $R$ and the horizontal side of rectangle $Q'R'S'T'$ from $Q'$ to $R'$. Suppose the length of the horizontal side of rectangle $QRST$ is $l_1$ and the length of the horizontal side of rectangle $Q'R'S'T'$ is $l_2$. By counting the grid - squares, if $l_1 = 24$ (counting the number of grid - squares from $Q$ to $R$) and $l_2 = 12$ (counting the number of grid - squares from $Q'$ to $R'$).

Step2: Calculate the scale factor

The scale factor $k$ is given by the formula $k=\frac{l_2}{l_1}$. Substituting $l_1 = 24$ and $l_2 = 12$ into the formula, we get $k=\frac{12}{24}=\frac{1}{2}$.

Answer:

$\frac{1}{2}$