Question

#5 0.5 cm 4 cm → 1.5 cm 12 cm scale factor:

Explanation:

Step1: Recall scale - factor formula

The scale factor $k$ from an original figure to a new figure is given by the ratio of corresponding side - lengths. If $x$ is the side - length of the original figure and $y$ is the side - length of the new figure, then $k=\frac{y}{x}$.

Step2: Choose a pair of corresponding sides

We can choose the vertical sides. The original vertical side length is $0.5$ cm and the new vertical side length is $1.5$ cm.
$k = \frac{1.5}{0.5}$

Step3: Calculate the scale factor

$\frac{1.5}{0.5}=\frac{15}{5}=3$

Answer:

$3$