Binomial Distribution

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BINOMIAL DISTRIBUTION

Always has two outcomes, success and failure

 

X ~B (n, p)

 

n = fixed No. of trials, they are independent

p = prob of success

q = prob of failure

 

Mean = E(X) = m = np

Variance = Var(X) = s2 = np(1- p) = npq

 

Probability of r successes

P( X = r ) = n pr qn-r or use tables

r

 

Approximation

Normal approx Þbinomial X ~B (n, p) ÞX ~N (np , npq)

1. n large

2. np > 5

3. nq > 5

Poisson approx Þbinomial X ~B (n, p) ÞX ~Po (np)

1. n large

2. p small

1 of 1

Comments

djfarkjn

there are a few more ways to distinguish a binomial distribution

djfarkjn

- fixed number of trials

- probability is fixed for each event

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