Should I use Binomial or Poisson Distribution

HP · 2008-02-25 22:55:16

I have a question with which i'm unusre on what method to answer it:

'You are a quality manager at a computer company that delivers 1500 computers each week. On average 2 computers fail to work on arrival

(i) Name a probability distribution that could be used to model this situation

(ii) This week 4 computers fail to work on arrival. What is the probability of 4 or more computers failing to work, calculated using the distribution you have chosen'

I was leaning towards the decision of using poisson distribution because the question doesn't give an exact probability.

Am I correct in doing this?

Thanks

mathsyperson · 2008-02-26 02:48:39

Yup, that's the model I'd choose.
Another way of thinking about it is that if you did go for a Binomial distribution, the calculations would be far too difficult, due to the large number of trials performed.

Even if a Binomial distribution was more suitable, it could be approximated accurately with Poisson, because of the high number of trials and low probability of success.

HP · 2008-02-26 22:41:11

Hi again,

Thanks for the reply. I was just wondering, to work out the probability of 4 or more computers failing, would it be better to just work out the probability of 4 failing or should I calculate the probability of 0,1,2,3 computers failing?

mathsyperson · 2008-02-27 03:13:21

Yes, you'd have to do it the way you described. You could work out the probability of exactly 4 computers failing directly, but that wouldn't answer the question.

You'd need to find the individual probabilities of 0, 1, 2 and 3 computers failing, and them all together and then take that away from 1.

Math Is Fun Forum

#1 2008-02-25 22:55:16

Should I use Binomial or Poisson Distribution

#2 2008-02-26 02:48:39

Re: Should I use Binomial or Poisson Distribution

#3 2008-02-26 22:41:11

Re: Should I use Binomial or Poisson Distribution

#4 2008-02-27 03:13:21

Re: Should I use Binomial or Poisson Distribution

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