Sally is playing a board game and rolls two number cubes. let a = {the sum of the number cubes is odd} and let b = {the sum of the number cubes is divisible by 2}. list the outcomes in a ∩ b.

To be odd means that the number is not divisible by 2, so set A is the opposite of set B. The two sets have nothing in common. If a number is odd, then its not even, and vice versa. The intersection of set A and set B is the empty set.

Empty set

Note: To write the empty set, we could use curly braces with nothing inside them like this { } or we can use the symbol