In a packet containing $400$ screws,$120$ screws are defective. $A$ screw is picked up randomly from the packet. Then,the probability that the screw picked up is non-defective is .........

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

$A$ game of chance consists of spinning an arrow which comes to rest pointing at one of the numbers $1, 2, 3, \dots, 11, 12$ on a circular disc. All these outcomes are equally likely. Then, the probability that the arrow rests to point at $7$ is ..........

$A$ girl calculates that the probability of her winning the first prize in a lottery is $0.08$. If $6000$ tickets are sold,how many tickets has she bought?

Two unbiased dice are thrown once. Write all the possible outcomes of this experiment. What is the probability that the sum of numbers on two dice is $8$?

The probability of a non-leap year having $53$ Saturdays is .......