In a packet of $500$ screws,$80$ screws are defective. Find the probability that a screw selected at random from the packet is non-defective. (in $/25$)

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 ball is not blue.

Two balanced dice are rolled simultaneously. Then,the probability that the sum of numbers on the dice is $4$ is .........

$A$ card is drawn at random from a well-shuffled pack of $52$ cards. The probability of that card being a jack is $\ldots \ldots \ldots$

$A$ balanced die is rolled once. Then,the probability that the number on the die is a prime number is .........

$A$ circle with radius $7 \, cm$ is drawn at the centre of a rectangle $28 \, cm$ long and $22 \, cm$ broad. Find the probability that a ball hitting the rectangle hits the circle.