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NDA Math Statistics
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© examsnet.com
Question : 32
Total: 100
If the correlation coefficient between x and y is 0.6, covariance is 27 and variance of y is 25, then what is the variance of x?
[NDA I 2018]
9/5
81/25
9
81
Validate
Solution:
σ
(
x
)
=
?
σ
2
(
y
)
=
25
⇒
σ
(
y
)
=
5
C
o
V
(
x
,
y
)
=
C
o
V
(
x
,
y
)
σ
(
x
)
σ
(
y
)
⇒
σ
(
x
)
=
C
o
V
(
x
,
y
)
r
(
x
,
y
)
σ
(
y
)
=
27
×
5
3
×
5
=
9
⟹ Variance of
x
=
σ
2
(
x
)
=
81
© examsnet.com
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