Multiple element systems question?

Question

A mircroscope with an overall magnification of 800 has an objective that magnifies by 200. What is the magnification of the eyepiece? If there are two other objectives that can be used, having magnifications of 100 and 400, what other total magnifications are possible?

Answer 1

M = M1M2

M2 = M / M1 = 800 / 200 = 4.00

The other possible magnifications are:

M = 100 x 4.00 = 400

M = 400 x 4.00 = 1600