A carton of 30 lightbulbs includes 5 defective ones. If 4 light bulbs are drawn at random (without replacement), what is the probability that;
(a) 2 of the selected light bulbs are defective.
(b) Not all the selected light bulbs are defective.
Sampling Without Replacement and defective light bulbs are investigated. The solution is detailed and well presented. The response received a rating of "5/5" from the student who originally posted the question.