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 either black or white.

The probability of getting the number $7$ while throwing a balanced die once is ...........

The probability of the month of April in any year having $5$ Sundays is ......... (in $/7$)

Someone is asked to take a number from $1$ to $100$. The probability that it is a prime number is

At a toy shop,there are $10$ toys in a box of which $3$ toys are defective. $A$ customer would purchase a non-defective toy only. The probability that a toy selected at random from the box is purchased by the customer is ..............

The probability of getting an even number while throwing a balanced die once is ...........