Let X be a random variable with distribution
|
X |
1 |
2 |
3 |
|
P(X) |
0.3 |
0.5 |
0.2 |
1
The value of E(X) is 1.9
2
The standard deviation of X is 0.7
3
The value of E(X2) is 4.1
4
The standard deviation of X is 0.5