Can someone help me work this out.

Question

Find the a) mean, b)variance and c) standard deviation for the probability distribution below

K Pr(X=k)
0 0.4
1 0.2
2 0.3
3 0.1

For mean I came up with 1.1
0(0.4)+1(0.2)+2(0.3)+3(0.1)

For variance I came up with 1.09
0.4(0-1.1)sq+0.2(1-1.1)sq+0.3(2-1.1)sq+0.1(3-1.1)sq
sq means squared

and for standard deviation I came up with 1.0440.
square root of 1.09

I did all of the steps but I am unsure.
Can someone show me theirs?

Thanks in advance.

Answer 1

What you did seems correct to me.