1. The problem statement, all variables and given/known data Suppose the lens in a human eye has far focal length equal to f0 = .0405 m, for distant objects to be in focus. (a) An object K is 1.72 m from the lens. How much should the focal length change to focus on the object K? (b) What is the magnification ( = image size divided by object size) for the object K? 2. Relevant equations 1/do + 1/di = 1/f 3. The attempt at a solution I figured the image distance (di) to be .0415 m, but I'm unsure of how much the focal length should change to focus on the object K. I tried subtracting the object distance from the focal length (vice versa), doesn't work. I tried subtracting the image distance from the focal length (vice versa), didn't work. I tried subtracting the object distance from the image distance (vice versa), incorrect. Also, di/do is not giving me the correct magnification, it is not .241. Someone help please. It looks like I'm going to miss my deadline but I still need to know how to solve this type of problem for the test.