Two dice are thrown simultaneously. What is the probability that the sum of the numbers appearing on them is a prime number?

From a deck of cards, cards are taken out with replacement. What is the probability that the fourteenth card taken out is an ace?

IF A and B are two events such that P(A) = 0.5, P(B) = 0.6 and P(A $$\cap$$ B) = 0.4, then what is P($${\overline {A \cup B} }$$) equal to ?

A problem is given to three students A, B and C whose probabilities of solving the problem are $${1 \over 2},{3 \over 4}$$ and $${1 \over 4}$$ respectively. What is the probability that the problem will be solved if they all solve the problem independently?