(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The second problem in thispic

http://www.imagestation.com/picture/sraid220/p4c1709bad2d17fb97ea36c875b20474c/ebc1f71f.jpg [Broken]

2. Relevant equations

Second problem: For bernoulli trials, if Sn= x1+x2+...+xn is the number of successes, then E(Sn)=np, V(Sn)=npq, D(Sn)=square root of V(Sn)

3. The attempt at a solution

For the 2nd problem I have:

A.) I do not know what they mean by common distribution.

Sj = x1+x2+x3+x4+...+xj

Expected value of Xj= sum of (Xj) * probability of (Xj)

Variance = (j-1)*(probability of (Xj)) * (1 - probability of (Xj))

Standard deviation is the square root of variance

B.) E(Tn)= n * P(Tn)

V(Tn) = n * P(Tn) * (1-P (Tn))

C.) For coin tossing:

E(nth occurance of head) = n * (1/2)

V(nth offucence of head) = n * (1/2) * (1/2)

I really am not sure about my work. I have been trying it all day. Any guidance would be helpful. Thank you.

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# Homework Help: Two probability problems

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