Let X be a random variable with distribution. x - 2 - 1 3 4 6 P ( X = x ) 1 5 a 1 3 1 5 b If the mean of X…

Let X be a random variable with distribution.

x -2 -1 3 4 6
P(X=x) 15 a 13 15 b

If the mean of X is 2.3 and variance of X is σ2, then 100σ2 is equal to :

Solution

Given mean is μ=pixi=2.3

-25-a+1+45+6b=2.3

6b-a=0.9   ...(1)

Also pi=1

15+a+13+15+b=1

a+b=415   ...(2)

Solving, we get a=110; b=16

Variance is σ2=pixi2-μ2

σ2=15(4)+110(1)+13(9)+15(16)+16(36)-5.29

σ2=7.81

100σ2=781

Asked in: JEE Main 2021 (01 Sep Shift 2)

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