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

$A \cap C$

If $X$ and $Y$ are two sets such that $X$ has $40$ elements, $X \cup Y$ has $60$ elements and $X$ $\cap\, Y$ has $10$ elements, how many elements does $Y$ have?

If $A=\{x \in R:|x|<2\}$ and $B=\{x \in R:|x-2| \geq 3\}$ then

Let $A=\{1,2,3,4,5,6,7,8,9,10\}$ and $B=\{2,3,5,7\} .$ Find $A \cap B$ and hence show that $A \cap B = B$

Show that $A \cap B=A \cap C$ need not imply $B = C$

If $A=\{1,2,3,4\}, B=\{3,4,5,6\}, C=\{5,6,7,8\}$ and $D=\{7,8,9,10\} ;$ find

$A \cup B \cup D$