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

$A$ triangular target with sides measuring $5 \, cm, 12 \, cm$,and $13 \, cm$ is drawn on a square board with side $20 \, cm$. Find the probability that a dart hitting the board hits the target.

In a game,the entry fee is $Rs. 5$. The game consists of tossing a coin $3$ times. If one or two heads show,Sweta gets her entry fee back. If she throws $3$ heads,she receives double the entry fee. Otherwise,she will lose. For tossing a coin three times,find the probability that she:
$(i)$ loses the entry fee.
$(ii)$ gets double the entry fee.
$(iii)$ just gets her entry fee back.

If an event cannot occur,then its probability is

Two balanced dice are rolled simultaneously. Then,the probability that the sum of numbers on the dice is $12$ is ........

There are $5$ red,$8$ white,and $4$ green balls in a box. $A$ ball is drawn at random from the box. Find the probability that the ball drawn is not green.