Question

The following table shows the probability distribution for a discrete random variable.
X- 12,15,17,20,22,24,25,30
P(X)- 0.07,0.21,0.17,0.25,0.05,0.04,0.13,0.08
What is the mean of this discrete random variable. That is, what is E(X), the expected value of X?
I got 19.59,. Is this right?

Answer 1

expected value is: number*probability added up for each one

Answer 2

\[\sum_{i=1}^{N}X_i*P(X_i)\]

Answer 3

lets see how the google plays with this:

12(0.07)+15(0.21)+17(0.17)+20(0.25)+22(0.05)+24(0.04)+25(0.13)+30(0.08)

http://www.google.com/search?aq=f&ix=acb&sourceid=chrome&ie=UTF-8&q=12(0.07)%2B15(0.21)%2B17(0.17)%2B20(0.25)%2B22(0.05)%2B24(0.04)%2B25(0.13)%2B30(0.08)

19.59 looks right to me

Answer 4

Thank you! ;) outstanding.