If P(ABC) = 0.2, are A and C mutually exclusive? Explain.

Assuming P(ABC) means P(A intersect B instersect C) (where "intersect" is an upside down U), then no.

Because if they were mutually exclusive, that would mean the probability of both A and C occuring would be 0. But the probability if A, B and C all occuring is non-zero,
=> the probability if A and C both occuring is non-zero
=> A and C are not mutually exclusive