Question

I am to find the mean, variance, and standard deviation for the probability distribution. I don't even know where to start. Here is the problem

x P(x)
0 0.19
1 0.32
2 0.28
3 0.21

Answer 1

Formula for the mean:
SUM [x * P(x)]

Take x times P(x) for each value listed. Then add for the mean.

Formula for the variance:
{SUM [x^2 * P(x)] - mean^2}

Square each x. Then take x^2 times P(x) for each value. Add up the values for a total, then subtract mean squared from that total.

For standard deviation:
Take the square root of the variance.

I hope this will help.