# Test: Probability I - Ambitious

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Question 1:   How many four-digit numbers can you get out of ?
$24$
$30$
$18$
$9$
Question 2:   There are $\text{\hspace{0.17em}}19\text{\hspace{0.17em}}$ balls in the box: $\text{\hspace{0.17em}}10\text{\hspace{0.17em}}$ of red ones and $\text{\hspace{0.17em}}9\text{\hspace{0.17em}}$ of blue ones. In how many ways can two balls of the same color be picked?
$162$
$81$
$9$
$171$
Question 3:   In how many ways can you pick a captain and his deputy in a group of $\text{\hspace{0.17em}}23\text{\hspace{0.17em}}$ soldiers?
$253$
$506$
$\frac{2}{23}×100%$
$\frac{2}{23!}$
Question 4:   John has $\text{\hspace{0.17em}}4\text{\hspace{0.17em}}$ cats. In how many ways he can take $\text{\hspace{0.17em}}2\text{\hspace{0.17em}}$ of them in his hands (one - in left hand, another - in right)?
$8$
$24$
$2$
$12$
Question 5:   Three passengers walk into the elevator of the $\text{\hspace{0.17em}}11$-floor building (ground floor is not included). In how many ways all three passengers can get out on different floors?
$165$
$33$
$990$
$495$
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