Math (Statistics)
posted by Heather on .
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

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.