Answer:
C. 44 cm
Explanation:
We can solve the problem by using the lens equation:
[tex]\frac{1}{f}=\frac{1}{p}+\frac{1}{q}[/tex]
where
f is the focal length
p = 30 cm is the distance of the object from the mirror
q is the distance of the image from the mirror
We also know that the magnification is
[tex]M=-\frac{q}{p}=+3.2[/tex]
So
[tex]q=-3.2p=-3.2(30)=-96 cm[/tex]
Substituting into the first equation, we find f:
[tex]\frac{1}{f}=\frac{1}{30}-\frac{1}{96}=0.0229 cm^{-1} \rightarrow f=43.7 cm \sim 44 cm[/tex]
