There are $5$ white,$7$ red,$4$ black,and $2$ blue identical balls in a box. One ball is selected at random from the box. Find the probability that the selected ball is either white or blue.

$A$ card is selected at random from a well-shuffled pack of $52$ cards. Find the probability that the selected card is that of spades.

Two dice are thrown together. Find the probability that the product of the numbers on the top of the dice is
$(i) \, 6$
$(ii) \, 12$
$(iii) \, 7$

$A$ game of chance consists of spinning an arrow which comes to rest pointing at one of the numbers $1, 2, 3, 4, 5, 6, 7, 8$ (see figure),and these are equally likely outcomes. What is the probability that it will point at:
$(i)$ $8?$
$(ii)$ an odd number?
$(iii)$ a number greater than $2?$
$(iv)$ a number less than $9?$

$A$ card is selected at random from a well-shuffled pack of $52$ cards. Find the probability that the selected card is the queen of hearts.

$A$ child's game has $8$ triangles of which $3$ are blue and the rest are red,and $10$ squares of which $6$ are blue and the rest are red. One piece is lost at random. Find the probability that it is a
$(i)$ triangle
$(ii)$ square
$(iii)$ square of blue colour
$(iv)$ triangle of red colour