The associative property is a property of some binary operations, which means that rearranging the parentheses in an expression will not change the result. In propositional logic, associativity is a valid rule of replacement for expressions in logical proofs.
One advantage is that you don't have to count out your money when you are cashing in. But one con is that people can forge your signature if you give it to them and their dishonest.
In a stack of 24, the 2 mediums are odd and even cards in this question. This means that 1/2 the cards are even and 1/2 are odd. To get a even card once is a 1/2 chance, then to get it again is 1/2 x 1/2 chance or 1/4 chance. This is what I think.