Question

How to find mean and variance of a probability distribution?

Answer 1

for example:
Step 1: Convert all the percentages to decimal probabilities. For example:
95% = .95
2% = .02
2% = .02
1% = .01

Step 2: Construct a probability distribution


Step 3:  Multiply the values in each column. (In other words, multiply each value of X by each probability P(X).)
Referring to our probability distribution table:
0 × .95 = 0
1 × .02  = .02
2 × .02  = .04
3 × .01 = .03

Step 4: Add the results from step 3 together.
0 + .02 + .04 + .03 = .09 is the mean.

You’re done finding the mean for a probability distribution!