A box contains 12 lights bulbs, of which 4 are defective. All bulbs look alike and have equal chance of being chosen. 3 light bulbs are selected from the box to check the quality.
a. List all the possible outcomes
b. find the probability that all 3 are defective
c. Find the probability that exactly two of the three chhosen are defective
d. Find the probability that a least one of the three are defective.