Answer
$92cm$
Work Step by Step
We know that
$m=-\frac{d_i}{d_{\circ}}$
$\implies d_i=-md_{\circ}$
We plug in the known values to obtain:
$d_i=-2.2\times 25cm=-55cm$
We also know that
$\frac{1}{f}=\frac{1}{d_{\circ}}+\frac{1}{d_i}$
$\implies \frac{1}{f}=\frac{d_{\circ}d_i}{d_{\circ}+d_i}$
$\implies \frac{1}{f}=\frac{25\times (-55)}{25-55}cm$
$\frac{1}{f}=45.83cm$
Now we can find the required radius of curvature as
$R=2f$
We plug in the known values to obtain:
$R=2(45.83)$
$R=92cm$
