Question

Find the standard deviation of the following data. Round your answer to one decimal place. x −6 −5 −4 −3 −2 −1 P(X=x) 0.1 0.1 0.3 0.1 0.1 0.3

Answer 1

Solution:

x	P(x)	x * P(x)	x2 * P(x)
-6	0.1	-0.6	3.6
-5	0.1	-0.5	2.5
-4	0.3	-1.2	4.8
-3	0.1	-0.3	0.9
-2	0.1	-0.2	0.4
-1	0.3	-0.3	0.3
Sum	1	-3.1	12.5

Mean = X * P(X)

= -3.1

Standard deviation =

=X 2 * P(X) - 2

=  12.5 - (-3.1)2 = 2.89

Standard deviation = = 1.7