Question

a manufactrer produces lightbulbs that are packed into boxes of 100. if quality control studies indicate that 0.5% of lightbulbs produce are defective, what percentage of the boxes will contain if 2 or more defectives?

Answer 1

As n is large and p, the P (defective bulb), is small, use the Poisson approximation to the Binomial probability distribution.

0.5%=0.005

$\lambda=100(0.005)=0.5$

$P(x \ge2)=1-P(x \le1)=1-0.9098=0.0902$