# Test: Probability - Challenging

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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?
$\frac{1}{4}$
$\frac{4}{6}$
$\frac{1}{3}$
$\frac{1}{2}$
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 $5$ ?
$\frac{5}{28}$
$\frac{1}{28}$
$\frac{3}{28}$
$\frac{1}{5}$
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 $8$ ?
$\frac{8}{15}$
$\frac{1}{15}$
$\frac{7}{8}$
$\frac{7}{15}$
Question 4:   A girl picks one natural number from $1$ to $20$ . What is the probability that the number is a factor of $20$ ?
$\frac{1}{10}$
$\frac{3}{20}$
$\frac{1}{20}$
$\frac{3}{10}$
Question 5:   What is the probability of getting an odd number when a fair dice is thrown?
$\frac{1}{3}$
$\frac{1}{6}$
$\frac{1}{2}$
$\frac{2}{3}$
Question 6:   How many different ways six people can stand in a queue?
$36$
$620$
$12$
$720$
Question 7:   Calculate ${A}_{6}^{3}$
$18$
$102$
$120$
$3$
Question 8:   In how many different ways is it possible to pick any $4$ books from a set of $7$ books?
$35$
$44$
$74$
$28$
Question 9:   Solve the equation for $a$ : ${C}_{a}^{a-2}=45$
$10$
$47$
$20$
$30$
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?
$0.24$
$0.8$
$0.4$
$0.13$