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UPSC NDA Math Model Paper 4
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© examsnet.com
Question : 61
Total: 120
Mean and standard deviation of 100 items are 50 and 4 respectively. The sum of all squares of the items is
251600
256100
266000
261600
Validate
Solution:
Given:
n
=
100
,
x
=
50
,
σ
=
4
From the formula
⇒
σ
2
=
∑
x
2
n
−
(
∑
x
n
)
2
⇒
σ
2
=
∑
x
2
n
−
x
2
⇒
∑
x
2
=
n
(
σ
2
+
x
2
)
=
100
(
16
+
2500
)
=
251600
Hence, option (1) is correct.
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