When two dice are thrown,what is the probability of getting a sum of $7$ (in $/36$)?

If $A, B, C$ are three events of a sample space such that $P(B)=\frac{3}{2} P(A)$ and $P(C)=\frac{1}{2} P(B)$, then which of the following is correct?

The probability that Krishna will be alive in $10$ years is $7/15$ and the probability that Hari will be alive in $10$ years is $7/10$. What is the probability that both will die within the next $10$ years (in $/150$)?

Two dice are thrown together. The probability that the sum of the two numbers will be a multiple of $4$ is

The probabilities of $A$ and $B$ dying in a year are $p$ and $q$ respectively. What is the probability that only one of them will be alive at the end of the year?

Person $A$ can solve $90 \%$ of the problems given in the book and Person $B$ can solve $70 \%$. Then,the probability that at least one of them will solve the problem selected at random from the book is