NIMCET 2013 Question Paper with solutions

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Question : 39 of 120

Marks: +1, -0

A random variable X has the distribution law as given below :

x	1	2	3
P (X = x)	0.3	0.4	0.3

The variance of the distrinution is:

0.4
0.6
2
N.O.T

Solution:

Variance

=z↖{-}(x_i-x↖{-})^2p_i

x↖{-}=z↖{-}p_ix_i=1×0.3+2×0.4+3×0.3=2

∴ Variance

=(1-2)^2×0.3+(2-2)^2×0.4+(3-2)^2×0.3=0.6

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