1. How many positive integers that <= 2001 can be evenly divided by 3 and 4 but not 5? 2. We have a string that's 20 cm in length, we'll cut it into 2 pieces and use one to form a square and another a circle. We want to minimize the total area so where to cut? 3. We'll draw a segment on each of the six faces of a cube, each from one midpoint of an edge to the midpoint of the opposite edge(so either horizontal or vertical). After this is done, what's the possibility of a ring appears around this cube?