9000140506
Level:
B
Simplify \(\frac{2!}
{1!} + \frac{3!}
{2!} + \frac{4!}
{3!}\).
\(9\)
\(\frac{29}
{6} \)
\(\frac{9}
{6}\)
\(\frac{12!+9!+8!}
{6!} \)
Combinatorics
9000139710
Level:
C
The wallet contains nine coins: three
\(1\)-Euro coins,
three \(2\)-Euro coins
and three \(5\)-Euro
coins. How many different amounts can be paid if we have to pay the amount exactly
and use just three coins for this payment?
\(\frac{5!}
{3!\, 2!}=10\)
\(\frac{5!}
{3!}=20\)
\(3^{3}=27\)
\(3!=6\)
9000140507
Level:
B
Simplify for \(n\in \mathbb{N}\).
\[
\frac{(n + 2)!}
{n! + (n + 1)!}
\]
\(n + 1\)
\(\frac{n!+2}
{2n!+1}\)
\(\frac{n+2}
{2n+1}\)
\(\frac{n!+2!}
{2n!+1!}\)
9000139307
Level:
A
There are \(10\)
students hurrying to the dining room. Find the number of possibilities how can be
these students ordered into the row to get the meal.
\(10!=3\:628\:800\)
\(10\)
\(10^{10}\)
\(\frac{10!}
{10} =362\:880\)
9000140508
Level:
B
Simplify for \(n\in \mathbb{N}\).
\[
\frac{(n + 1)!}
{n! - (n + 1)!}
\]
\(- 1 - \frac{1}
{n}\)
\(n + 1\)
\(n! + 1\)
\(- \frac{n+1}
{(n-1)!}\)
9000139703
Level:
A
The box contains \(5\)
red crayons, \(4\)
yellow crayons and \(2\)
green crayons. The crayons are removed from the box and arranged in a
line. How many different color patterns can be obtained by this procedure?
\(\frac{11!}
{5!\, 4!\, 2!}=6\:930\)
\(5\cdot 4\cdot 2=40\)
\(5!\, 4!\, 2!=5\:760\)
\(\left (5!\, 4!\right )^{2}=8\:294\:400\)
9000140502
Level:
B
Simplify for \(n\in \mathbb{N}\).
\[
\frac{(n + 1)!}
{(n - 1)!}
\]
\(n^{2} + n\)
\((n + 1)^{2}\)
\(\frac{n+1}
{n-1}\)
\(- 1\)
9000139704
Level:
C
There are \(5\)
different kinds of cakes in a shop. Find the number of possibilities how to buy
\(8\) cakes in this shop.
(There is more than \(8\)
cakes of each kind available.)
\(\frac{12!}
{8!\, 4!}=495\)
\(5!\, 8!=4\:838\:400\)
\(5^{8}=390\:625\)
\(\frac{8!}
{5!\, 3!}=56\)
9000140503
Level:
B
Simplify for \(n\in \mathbb{N}\).
\[
\frac{(n + 1)! + (n - 1)!}
{n!}
\]
\(\frac{n^{2}+n+1}
{n} \)
\(2\)
\(n^{2} - 1\)
\(\frac{n^{2}-n+1}
{n} \)
9000139705
Level:
A
From the group of \(10\) boys
and \(5\) girls we have to
select a small group of \(3\)
boys and \(2\)
girls. How many possibilities exist for this choice?
\(\frac{10!}
{7!\, 3!}\cdot \frac{5!}
{3!\, 2!}=1\:200\)
\(5^{10}=9\:765\:625\)
\(10\cdot 5!\, 3!=7\:200\)
\(5\cdot \frac{10!}
{3!} =3\:024\:000\)