— 31 —
n
!
(
n
r
)!
n
!
n
!(
n
r
)!
Permutation
• Input range:
n
r
0 (
n
,
r
: integers)
• Formula:
n
P
r
Combination
• Input range:
n
r
0 (
n
,
r
: integers)
• Formula:
n
C
r
Population Standard Deviation
n
n
i
1
n
(
xi
–
x
)
2
n
x
2
– (
x
)
2
/
n
Sample Standard Deviation
n
–
1
n
– 1
i
1
n
(
xi
–
x
)
2
x
2
– (
x
)
2
/
n
n
– 1
Arithmetic Mean
o
n
i
1
n
xi
x
n