Answer
$-33cm$
Work Step by Step
We can use the values given on table 34-5 in equation 34-8 to find the radius of the mirror, $r$.
$\frac{n_1}{p}+\frac{n_2}{i}=\frac{n_2-n_1}{r}$
solving for r, we obtain:
$r=(\frac{n_1}{p}+\frac{n_2}{i})^{-1}*(n_2-n_1)$
$r=(\frac{1.0}{10cm}+\frac{1.5}{-13cm})^{-1}*(1.5-1.0)$
$r=-33cm$