I have 4 "containers", each with elements a, b, c, d, e. Each step, I randomly choose one element from each container and write them together. For example, I could have an outcome of "aacd" and "eead". How many of the combinations have a, b, c, or d for at least 3 of the 4 slots? (for example, "aabb" would count but "adee" would not)
From my calculations, I know there are 625 possible combinations.
How do I solve this from here?