Answer
The film should be about 0.1054 m from the lens. The picture will be about 5.8 m wide.
Work Step by Step
Apply the lens equation.
$$\frac{1}{d_o}+\frac{1}{d_i}=\frac{1}{f}$$
$$\frac{1}{d_o}+\frac{1}{25.5m}=\frac{1}{0.105m}$$
$$d_o=\frac{fd_i}{d_i-f}=\frac{(0.105m)(25.5m)}{25.5m-0.105m}=0.1054m$$
Find the width of the image on the screen from equation 23–9 for the magnification $m=\frac{h_i}{h_o}=-\frac{d_i}{d_o}$
$$|h_i|=|\frac{d_i}{d_o}h_o|=\frac{25.5m}{0.1054m}(0.024m)=5.8m$$
