AP ICET 2017 Shift 2 Paper

Question : 145 of 200

Marks: +1, -0

The observations

x_i(i=1,2,....15)

of an experiment it is given

∑_{i=1}^{15}x_{i}=170

and

∑_{i=1}^{15}x_{i}^{2}=2830

.Later it is noticed that one

x_i

is entered as 20 instead of the collect value 30. The correct value of their variance is

Solution:

Corrected

Σx_i=170–20+30=180

Corrected

Σx_i^2=2830–(20)^2+30^2=3330

Here, n = 15
∴ Correct variance

=1/nΣx__i^2-(1/nΣx_i)^2

={3330}/{15}-({180}/{15})^{2}=222-144=78

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