Please help with density function question solving for sigma(x)?

Homwork says: find E(X), Var(X), sigma(X) of a random variable X let x be given by its density function F(x) such that f(x) = 0, if x <= 1 f(x) = 1/4, if 1 < x <= 5 f(x) = 0, if x > 5 I think I solved E(X) and Var(x) correctly. I found that E(x)= 5/2 and Var(x)=11/4. Am I correct? I need... show more Homwork says:
find E(X), Var(X), sigma(X) of a random variable X
let x be given by its density function F(x) such that

f(x) = 0, if x <= 1
f(x) = 1/4, if 1 < x <= 5
f(x) = 0, if x > 5

I think I solved E(X) and Var(x) correctly. I found that E(x)= 5/2 and Var(x)=11/4. Am I correct? I need to solve for sigma(x) too. Please help.
2 answers