s
a
m
p
l
e
s
i
z
e
n
2
0
n
u
m
b
e
r
o
f
m
a
r
k
e
d
b
a
l
l
s
k
2
5
t
o
t
a
l
n
u
m
b
e
r
o
f
b
a
l
l
s
N
1
0
0
m
e
a
n
:
k
n
N
=
5
.
0
0
v
a
r
i
a
n
c
e
:
k
n
1
-
k
N
(
-
n
+
N
)
(
-
1
+
N
)
N
=
3
.
0
3