For three events A, B and C,
P(Exactly one of A or B occurs)
=P(Exactly one of B or C occurs)
=P(Exactly one of C or A occurs)=
$\large\frac{1}{4}$ and
P(All the three events occur
simultaneously)=$\large\frac{1}{16}$.Then the probability that at least one of the events occurs, is :