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Question
Mathematics
If μ is the mean distribution of yi,fi then Sigma fi yi-μ is equal to:
Q. If
μ
is the mean distribution of
{
y
i
,
f
i
}
,
then
Σ
f
i
{
y
i
−
μ
}
is equal to:
2285
192
KEAM
KEAM 2001
Report Error
A
MD
B
SD
C
0
D
relative frequency
E
none of these
Solution:
∵
μ
is mean of distribution
{
y
i
,
f
i
}
.
∴
μ
=
f
1
+
f
2
+
.....
+
f
n
y
1
f
1
+
y
2
f
2
+
....
+
y
n
f
n
⇒
(
f
1
+
f
2
+
.....
+
f
n
)
μ
=
y
1
f
1
+
y
2
f
2
+
...
+
y
n
f
n
Now,
Σ
f
i
(
y
i
−
μ
)
=
(
f
1
y
1
+
f
2
y
2
+
.....
+
f
n
y
n
)
−
(
f
1
+
f
2
+
....
f
n
)
μ
=
(
f
1
+
f
2
+
...
+
f
n
)
μ
−
(
f
1
+
f
2
+
....
+
f
n
)
μ
=
0