# Statisitics - Random Variables

1. Mar 4, 2012

### tjackson

1. The problem statement, all variables and given/known data

There is a population of 30 elk. 6 elk are captured, tagged and then released into the wild. Then later 5 elk are captured, what is the probability that k elk are tagged?

2. Relevant equations

p=6/30 = 1/5

P = $\stackrel{n}{k}$ * pk * (1-p)k

$\stackrel{n}{k}$ is n choose k

3. The attempt at a solution

plug in the values.

but the big question I have is: Is this a binomial RV?

2. Mar 4, 2012

### 80past2

I think this would be hypergeometric.

3. Mar 4, 2012

### 80past2

to elaborate, the way you have it, as a binomial, would mean that each deer caught has a 6/30 chance of being tagged. but this is not the case. if you catch a deer and it is tagged, then there are 24 untagged deer and 5 tagged deer remaining. so on your next catch, you would a 5/29 chance of catching a tagged deer. but you can use a hypergeometric distribution on this to make it a little easier.