Let $A$ and $B$ be events such that $P(A)=0.4, P(B)=0.5$ and $P(A\cup B)=0.7$. Which of the following are true? (For sets $A,B,A\Delta B=(A^c\cap B)\cup (A\cap B^c))$.
- $A$ and $B$ are mutually exclusive
- $A$ and $B$ are independent
- $P(A\Delta B)= 0.1$
- $P(A^c \cup B^c)=0.8$