Question

Calculate the standard deviation σ of X for the probability distribution. (Round your answer to two decimal places.) σ = x 10 20 30 40 P(X = x) 3 /10 1/ 5 1/ 5 3/ 10

Answer 1

Solution:

x	P(x)	x * P(x)	x2 * P(x)
10	0.3	3	30
20	0.2	4	80
30	0.2	6	180
40	0.3	12	480
Sum	1	25	770

Mean = X * P(X)

= 25

Standard deviation =

=X 2 * P(X) - 2

=  770 - (25)2 = 145

Standard deviation = = 12.04