ANSWER:
7.4 cm
STEP-BY-STEP EXPLANATION:
Given:
Object distance (o) = 98 cm
Image distance (i) = 8 cm
We can determine the focal length using the following formula:
[tex]\begin{gathered} \frac{1}{f}=\frac{1}{o}+\frac{1}{i} \\ \\ \text{ We replacing:} \\ \\ \frac{1}{f}=\frac{1}{98}+\frac{1}{8} \\ \\ \frac{1}{f}=\frac{98+8}{98\cdot8} \\ \\ f=\frac{98\cdot8}{98+8}=\frac{784}{106} \\ \\ f=7.396\cong7.4\text{ cm} \end{gathered}[/tex]The focal length of the lens is 7.4 cm
