week 3 Flashcards
1
Q
n!
A
n factorial
n x (n-1)!
eg 4! = 4x3x2x1
2
Q
0!
A
1
3
Q
1!
A
1
4
Q
2!
A
2
5
Q
3!
A
6
6
Q
4!
A
24
7
Q
5!
A
120
8
Q
circular permutations
number of ways n objects can be arranged around a circle
A
(n-1)!
9
Q
(n k)
A
number of ways to select k objects from a set of n objects
= n!/k!(n-k)!
10
Q
(0 0)
A
1
11
Q
(1 0)
A
1
12
Q
(1 1)
A
1
13
Q
(2 0)
A
1
14
Q
(2 1)
A
2
15
Q
(2 2)
A
1
16
Q
(3 0)
A
1
17
Q
(3 1)
A
3
18
Q
(3 2)
A
3
19
Q
(3 3)
A
1
20
Q
(4 0)
A
1
21
Q
(4 1)
A
4
22
Q
(4 2)
A
6
23
Q
(4 3)
A
4
24
Q
(4 4)
A
1
25
Q
(n 0)
A
1
there is 1 way to choose 0 objects ( don’t choose any)
26
Q
(n 1)
A
n
there are n ways to choose 1 object
27
Q
(n n)
A
1
there is 1 way to choose n objects ( choose all of them)
28
Q
(n k)
A
(n n-k)
eg (5 2) = (5 5-2) (5 3)
29
Q
selecting k objects from a set of n objects and arranging around the k objects
A
n!/ (n-k)!
30
Q
selecting k objects from a set of n objects and arranging around the k objects in a circle
A
1/k n!/k(n-k)!
