One number is selected at random from one-digit natural numbers. The probability of that number being even is $\ldots \ldots \ldots$

Three unbiased coins are tossed simultaneously. Then,the probability of receiving at least two heads is ..........

$A$ coin is tossed two times. Find the probability of getting at most one head.

An unbiased coin is tossed thrice. Then,the number of total outcomes is ............

The probability of an event $K$ satisfies ...............

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.