Question

Calculate the standard deviation σ of X for the probability distribution. (Round your answer to two decimal places.)
σ =

x	0	1	2	3
P(X = x)	0.1	0.2	0.3	0.4

Answer 1

Solution:

x	P(x)	x * P(x)	x2 * P(x)
0	0.1	0	0
1	0.2	0.2	0.2
2	0.3	0.6	1.2
3	0.4	1.2	3.6
Sum	1	2	5

Mean = X * P(X)

= 2

Standard deviation =

=X 2 * P(X) - 2

=  5 - (2)2 = 1

Standard deviation = = 1