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JEE Main Math Class 12 Statistics Questions Part 1 Questions
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© examsnet.com
Question : 1
Total: 115
Let the six numbers
a
1
,
a
2
,
a
3
,
a
4
,
a
5
,
a
6
be in A.P. and
a
1
+
a
3
=
10
. If the mean of these six numbers
19
2
and their variance is
σ
2
, then
8
σ
2
is equal to
[24-Jan-2023 Shift 2]
220
210
200
105
Validate
Solution:
a
1
+
a
3
=
10
=
a
1
+
d
⇒
5
a
1
+
a
2
+
a
3
+
a
4
+
a
5
+
a
6
=
5
7
⇒
6
2
[
a
1
+
a
6
]
=
57
⇒
a
1
+
a
6
=
19
⇒
2
a
1
+
5
d
=
19
and
a
1
+
d
=
5
⇒
a
1
=
2
,
d
=
3
Numbers :
2
,
5
,
8
,
11
,
14
,
17
Variance
=
σ
2
=
mean of squares-square of mean
=
2
2
+
5
2
+
8
2
+
(
11
)
2
+
(
14
)
2
+
(
17
)
2
6
−
(
19
2
)
2
=
699
6
−
361
4
=
105
4
8
σ
2
=
210
© examsnet.com
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