p
a
r
a
m
e
t
e
r
r
1
3
.
p
a
r
a
m
e
t
e
r
r
2
6
.
m
e
a
n
:
r
2
r
2
-
2
=
1
.
5
0
v
a
r
i
a
n
c
e
:
2
2
r
2
(
r
1
+
r
2
-
2
)
r
1
(
r
2
-
4
)
2
(
r
2
-
2
)
=
5
.
2
5
0