In a single throw of $2$ dice,find the probability of getting a total of $8.$

$A$ card is drawn from a pack of $52$ cards. Find the probability of getting a spade,an ace,or a red card.

In a box,there are $8$ red,$7$ blue and $6$ green balls. One ball is picked up at random. What is the probability that it is neither red nor green?

Two numbers $a$ and $b$ are chosen at random from the set of first $30$ natural numbers. The probability that $a^2 - b^2$ is divisible by $3$ is

$2$ dice are thrown. Find the probability of getting the product as a perfect square (square of a natural number).

$A$ bag contains $3$ red and $5$ black balls and a second bag contains $6$ red and $4$ black balls. $A$ ball is drawn from each bag. The probability that one is red and the other is black,is