Two dice are tossed once. The probability of getting an even number at the first die or a a total of 8 is

The probability that at least one of A and B occurs is 0.6. If A and B occur simultaneously with probability 0.3, then P(A') + P(B') is

4 boys and 2 girls occupy seats in a row at random. Then the probability that the two girls occupy seats side by side is

A coin is tossed again and again. If tail appears on first three tosses, then the chance that head appears on fourth toss is