A student appears for tests, $$I$$, $$II$$ and $$III$$. The student is successful if he passes either in tests $$I$$ and $$II$$ or tests $$I$$ and $$III$$. The probabilities of student passing in tests $$I$$, $$II$$ and $$III$$ are $$p, q$$ and $${1 \over 2}$$ respectively. If the probability that the student is successful is $${1 \over 2}$$, then

The probability that at least one of the events $$A$$ and $$B$$ occurs is $$0.6$$. If $$A$$ and $$B$$ occur simultaneously with probability $$0.2,$$ then $$P\left( {\overline A } \right) + P\left( {\overline B } \right)$$ is

A box contains $$24$$ identical balls of which $$12$$ are white and $$12$$ are black. The balls are drawn at random from the box one at a time with replacement. The probability that a white ball is drawn for the $$4$$th time on the $$7$$th draw is

Three identical dice are rolled. The probability that the same number will appear on each of them is