Posted by **Yvonne** on Wednesday, November 9, 2011 at 1:23pm.

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.