Question

X is the number of dollars gained or lost each day playing cards. The distribution of X is below. Give the mean and standard deviation of X. PLEASE SHOW ALL YOUR WORK

X	P(X)
0	0.30
1	0.10
2	0.50
3	0.10

Answer 1

Solution:

x	P(x)	x * P(x)	x2 * P(x)
0	0.3	0	0
1	0.1	0.1	0.1
2	0.5	1	2
3	0.1	0.3	0.9
Sum	1	1.4	3

Mean = X * P(X)

= 1.4

Standard deviation =

=X 2 * P(X) - 2

=  3 - (1.4)2 = 1.04

Standard deviation = = 1.0198