Question

The circumference of a circle changes from 20 to 4 after a dilation. What was the scale factor of the dilation?
A.1/25
B.1/5
C.5
D.25

Answer 1

Answer:

The answer is the option B

$\frac{1}{5}$

Step-by-step explanation:

we know that

To find the scale factor divide the circumference of the dilated circle by the circumference of the original circle

so

$scale\ factor=\frac{4}{20}=\frac{1}{5}$

Answer 2

Answer: B. $\frac{1}{5}$

Step-by-step explanation:

Given: The circumference of a circle changes from (pre-image)20 to 4(image) after a dilation.

Then, the scale factor is given by :-

$\text{Scale factor}=\frac{\text{Circumference of image}}{\text{Circumference of pre-image}}\\\\\Rightarrow\text{Scale factor}=\frac{4}{20}\\\\\Rightarrow\text{Scale factor}=\frac{1}{5}$

Hence, the scale factor after dilation =$\frac{1}{5}$