Answer:
5.33 cm
Explanation:
The lens equation states that:
[tex]\frac{1}{f}=\frac{1}{p}+\frac{1}{q}[/tex]
where
f is the focal length
p is the distance of the object from the lens
q is the distance of the image from the lens
In this problem,
p = 8 cm
q = 16 cm ( the sign is positive since the image is real, which means it is formed on the other side of the lens)
Substituting into the equation,
[tex]\frac{1}{f}=\frac{1}{8 cm}+\frac{1}{16 cm}=\frac{3}{16 cm}[/tex]
[tex]f=\frac{16}{3}cm=5.33 cm[/tex]
