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JEE Main Math Class 12 Statistics Questions Part 1 Questions
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© examsnet.com
Question : 2
Total: 115
The mean and variance of the marks obtained by the students in a test are 10 and 4 respectively. Later, the marks of one of the students is increased from 8 to 12 . If the new mean of the marks is
10.2
. then their new variance is equal to:
[25-Jan-2023 Shift 1]
4.04
4.08
3.96
3.92
Validate
Solution:
n
∑
i
=
1
x
i
=
10
n
n
∑
i
=
1
x
i
−
8
+
12
=
(
10.2
)
n
∴
n
=
20
Now
20
∑
i
=
1
x
i
2
20
−
(
10
)
2
=
4
⇒
20
∑
i
=
1
x
i
2
=
2080
20
∑
i
=
1
x
i
2
−
8
2
+
12
2
20
−
(
10.2
)
2
=
108
−
104.04
=
3.96
© examsnet.com
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