If $A$ and $B$ are disjoint,then $n(A \cup B)$ is equal to

State whether the following statement is true or false. Justify your answer.
${a, e, i, o, u}$ and ${a, b, c, d}$ are disjoint sets.

Let $E, F$ and $G$ be three events having probabilities $P(E) = \frac{1}{8}, P(F) = \frac{1}{6}$ and $P(G) = \frac{1}{4}$,and let $P(E \cap F \cap G) = \frac{1}{10}$. For any event $H$,if $H^C$ denotes its complement,then which of the following statements is(are) $TRUE$?
$(A) P(E \cap F \cap G^C) \leq \frac{1}{40}$
$(B) P(E^C \cap F \cap G) \leq \frac{1}{15}$
$(C) P(E \cup F \cup G) \leq \frac{13}{24}$
$(D) P(E^C \cap F^C \cap G^C) \leq \frac{5}{12}$

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 $A \cap B = B$.

Let $A$ and $B$ be two sets in the universal set. Then $A - B$ equals

Which of the following pairs of sets are disjoint?
${1, 2, 3, 4}$ and ${x : x \text{ is a natural number and } 4 \le x \le 6}$