Question

Suppose that 4% of produced computers by a company have defects, and defects occur independently of each other. a) Find the probability of exactly 2 defective computers in a shipment of fifty computers. b) Find the probability that a computer support specialist needs to test at least 10 computers in order to find one defective computer.

Answer 1

a)

Let X is a random variable shows the number of defective computers out of 50. Here X has binomial distribution with following parameters

n=50 and p=0.04

The probability of exactly 2 defective computers in a shipment of fifty computers is

Excel function used to find the probability is "=BINOMDIST(2,50,0.04,FALSE)"

b)

Here we need to use geometric distribution with parameter p =0.04. The required probability is