statistics - Random variable and trying to find \$E(N)\$ - Mathematics

# Statistics - Random variable and trying to find \$E(N)\$ - Mathematics

This preview shows pages 1–2. Sign up to view the full content.

3/27/13 statistics - Random variable and trying to find \$E(N)\$ - Mathematics math.stackexchange.com/questions/343975/random-variable-and-trying-to-find-en 1/2 Random variable and trying to find E ( N ) Given N = random variable that counts the fraction of trials that are successful trials = 12 N = S /12 S = number of successful trials E ( N ) =? i don't know how to find is there a specific formula? can someone help me out with this problem E ( N ) (statistics) (discrete­mathematics) edited 1 hour ago azimut 4,015 1 9 31 asked 1 hour ago jyuserersh 70 4 1 You can calculate the probability of a single experiment succeeding, right? Call that , as it's the same for every other experiment. So imagine each experiment as a whole being a single coin flip with probability of success p . So you're looking for the expected number of successes after 12 flips. Do you know which distribution this follows? p Alex 1 hour ago 1 Answer It is useful to introduce some notation. Define random variables by if the -th trial is successful, and if the trial is not successful. , , Q , X 1 X 2 X n = 1 X k k = 0 X k Then : the sum of the \$X_i% counts the number of successful trials.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern