**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?