Question

The probability distribution of a random variable X is given.

x	−4	−2	0	2	4
p(X = x)	0.2	0.1	0.3	0.2	0.2

Compute the mean, variance, and standard deviation of X. (Round your answers to two decimal places.)

Find mean, variance, and standard deviation

Answer 1

Solution :

x	P(x)	x * P(x)	x2 * P(x)
-4	0.2	-0.8	3.2
-2	0.1	-0.2	0.4
0	0.3	0	0
2	0.2	0.4	0.8
4	0.2	0.8	3.2
Sum	1	0.2	7.6

Mean = = X * P(X) = 0.2

Variance = X ² * P(X) - ² = 7.6 - 0.2² = 7.56

Standard deviation = = 2.75