1. An object placed 20 cm from a concave mirror forms an image that is three times as large as the object on a screen. Discover the radius of curvature of the mirror.
2. A hemispherical glass paperweight with R=10cm and n=1.5 has a bubble blemish located 8cm from the surface (vertex). At what distance from the surface does the image of the blemish appear to the outside observer?