Datasheet

280
T
T
h
h
e
e
‘
‘
P
P
r
r
o
o
b
b
a
a
b
b
i
i
l
l
i
i
t
t
y
y
’
’
g
g
r
r
o
o
u
u
p
p
o
o
f
f
f
f
u
u
n
n
c
c
t
t
i
i
o
o
n
n
s
s
This group of functions is provided to manipulate and evaluate probabilities
and probability distribution functions (p.d.f.’s).
COMB(n,r)
This function gives the value of
n
r
C using the formula
!
()!!
n
r
n
C
nrr
=
−
.
Eg. Find the probability of choosing 2 men and 3 women for a committee
of 5 people from a pool of 6 men and 5 women.
65
23
11
5
p



=



= 0.3247
Note: The reason for the single ‘COMB(6,2)’ above the main calculation is
to save time. Rather than using the MATH menu for every entry of the
COMB function, you can enter it once and then it repeatedly,
changing the parameters.
The ! function
The factorial function finds the number of
possible permutations of an entire collection of
n objects.
Eg. Find the number of ‘words’ that can be formed from the letters FRED.
No. of words = 4! = 24