Answer
a. 0.661m
b. 59.1.
Work Step by Step
a. $f_1=\frac{R}{2}=0.650m$.
For object and image both at infinity, the sum of the focal lengths equals the distance d between the eyepiece and the mirror vertex.
$$d=f_1+f_2=0.650m+0.0110m=0.661m$$
b. $|M|=\frac{f_1}{f_2}=\frac{0.650m}{0.011m}=59.1$
