1. The problem statement, all variables and given/known data The diameter of our disk-shaped galaxy, the Milky Way, is about 1.8E+5 light-years (ly). The distance to the Andromeda galaxy, which is the spiral galaxy nearest to the Milky Way, is about 1.8E+6 ly. If a scale model represents the Milky Way and Andromeda galaxies as dinner plates 26.9 cm in diameter, determine the distance between the centers of the two plates. 2. Relevant equations 1.8E5/1.8E6 = 26.9cm/x 3. The attempt at a solution Hey! So I attempted this question as a ratio: 1.8E5/1.8E6 = 26.9cm/x, and then solved for x, getting 269cm. I tried inputting this as the answer which was incorrect. Then I noticed that the question was asking for the distance between the centres of the 2 plates, so I tried adding both their radiuses (radii?), and got 269cm + 13.45cm + 13.45cm = 295.9cm. I tried inputting this as the answer, but it was incorrect as well. I feel like I might be completely messing up an incredibly simple question :P Thanks for any help!