Compact discs produced by a factory are packed in boxes. Each box contains 100 compact discs. It is known that 4% of the compact discs produced are defective.

a) Show that the probability that a box chosen at random will contain at most 2 defective compact discs is approximately 0.23

b) Find the probability that among 12 boxes chosen at random, there will be 4 boxes which contain at most 2 defective compact discs.

c) 70 boxes are chosen at random.Find the probability that between 10 boxes and 25 boxes inclusively, which contain at most 2 defective compact discs.