An object 10.0 cm tall is placed at the zero mark of a meter stick. A spherical mirror located at some point on the meter stick creates an image of the object that is upright, 4.00 cm tall, and located at the 42.0-cm mark of the meter stick.
(a) Is the mirror convex or concave?
(b) Where is the mirror?
(c) What is the mirror’s focal length?