#21 – This is a good example of a counting problem masking itself as a geometry problem. There is a very nice application of combination theory that makes it very simple:
#22 – This problem deals with analyzing the relative cost of an item. It is actually a great example of a very real world problem.
#23 – The geometry problem combines concepts about isosceles right triangles, circles and area. I always enjoy problems that combine multiple shapes like this:
#25 – This is one of my all-time favorite AMC 8 problems. It always takes me a little while to grasp what turns out to be a very simple concepts about the relationship between the square and the circle: