Question 1:   There are $4$ white and $8$ black balls in the basket. What is the probability that a ball picked at random is of white colour?

Question 2:   One tile is picked from a domino set. What is the probability that the picked tile will have a sum of dots equal to $5$ ?

Question 3:   There are $15$ balls in the box, numbered from $1$ to $15$ . One ball is picked at random from the box. What is the probability that the number of the picked ball is less than $8$ ?

Question 4:   A girl picks one natural number from $1$ to $20$ . What is the probability that the number is a factor of $20$ ?

Question 5:   What is the probability of getting an odd number when a fair dice is thrown?

Question 6:   How many different ways six people can stand in a queue?

Question 7:   Calculate ${{\displaystyle A}}_6^3$

Question 8:   In how many different ways is it possible to pick any $4$ books from a set of $7$ books?

Question 9:   Solve the equation for $a$ : ${{\displaystyle C}}_a^{a-2}=45$

Question 10:   There are $12$ white, $8$ yellow and $4$ red roses in the basket. $9$ roses are picked at random. What is the probability that there will be $4$ white, $3$ yellow and $2$ red roses in the bouquet?