A certain electronics company produces a particular type of vacuum tube. It has been observed that, on

Question:

A certain electronics company produces a particular type of vacuum tube. It has been observed that, on the average, three tubes of 100 are defective. The company packs the tubes in boxes of 400. What is the probability that a certain box of 400 tubes will contain
(a) r defective tubes?
(b) At least k defective tubes?
(c) At most one defective tube?
(d) Interpret your answers to (a), (b), and (c).