# What distribution should I use?

Being really bad in Statistics, need some help here. The problem is : We draw a sample of 20 laptops from a population of 1000 Laptops (serial numbers from 9000-9999). a. What distribution should i use for the serial number selected? b. What is the probability a randomly selected will be one of the last 200 to be produced. c. What is the probability the first 2 are from the last 100 to be manufactured. ** The purpose of sampling is to check the quality of the laptops, thus there are two outcomes: faulty or not-faulty.

• What distributions do you already know of? Jun 4, 2014 at 8:22
• I am a returning student to uni, thus i can't be sure what i'm supposed to know. I believe because the sample is small, i should go with binomial. b. the probability is 0.2 c. the prob is 0.1 * 0.1. Is it that simple? or im missing something there? Jun 4, 2014 at 8:29
• 'What distribution should i use for the serial number selected?' - do you mean for the serial numbers of the sampled laptops?
– Alex
Jun 4, 2014 at 8:38
• You should use the hypergeometric distribution. Jun 4, 2014 at 8:38
• I have edited my question. I assume that since we want to check the faulty laptops, the question refers to that fact given the sample. Hypergeometric was my initial thought, but the sample is small (<5%) Jun 4, 2014 at 8:50