Question

1. a drawing that measures 7 inches by 10 inches needs to be enlarged to 21 inches by 30 inches. what is the scale factor?

a. 2
b. 2.5
c. 3
d. 3.5

Explanation:

Step1: Define scale - factor formula

The scale factor $k$ for length is given by $k=\frac{\text{new length}}{\text{original length}}$.

Step2: Calculate scale - factor for one side

For the length side, the original length is 7 inches and the new length is 21 inches. So, $k=\frac{21}{7}=3$.

Step3: Check for the other side

For the width side, the original width is 10 inches and the new width is 30 inches. So, $k = \frac{30}{10}=3$. Since the scale - factor is the same for both length and width, the overall scale factor is 3.

Answer:

C. 3