If $X = \{a, b, c, d\}$ and $Y = \{f, b, d, g\},$ find $X \cap Y$.

If $A = \{3, 5, 7, 9, 11\}$,$B = \{7, 9, 11, 13\}$,$C = \{11, 13, 15\}$,and $D = \{15, 17\}$,find $A \cap B$.

Find the union of each of the following pairs of sets:
$A = \{1, 2, 3\}, B = \varnothing$

The simplified switching circuit for the following circuit is

Find the union of each of the following pairs of sets:
$A = \{ x : x \text{ is a natural number and } 1 < x \le 6 \}$
$B = \{ x : x \text{ is a natural number and } 6 < x < 10 \}$

Let $A = \{1, 2, 3, 4\}$ and $B = \{2, 3, 4, 5, 6\}$. Then $A \cap B$ is equal to: