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JEE Main Math Class 12 Statistics Part 2 Questions
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© examsnet.com
Question : 20
Total: 28
Let the mean and variance of 12 observations be
9
2
and 4 respectively. Later on, it was observed that two observations were considered as 9 and 10 instead of 7 and 14 respectively. If the correct variance is
m
n
, where
m
and
n
are coprime, then
m
+
n
is equal to
[8-Apr-2023 shift 2]
316
317
315
314
Validate
Solution:
Σ
x
12
=
9
2
∑
x
=
54
Σ
x
2
12
−
(
9
2
)
2
=
4
∑
x
2
=
291
∑
x
new
=
54
−
(
9
+
10
)
+
7
+
14
=
56
∑
x
new
2
=
291
−
(
81
+
100
)
+
49
+
196
=
355
σ
new
2
=
355
12
−
(
56
12
)
2
σ
new
2
=
281
36
=
m
n
m
+
n
=
317
Option (2)
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