MATHEMATICS · Multi-part · CBSE · Mathematics · Probability · Probability
Problem
A factory stores 20 light bulbs, of which exactly 4 are defective. Three bulbs are selected one after another without replacement for quality testing. Using the information given, answer the following:
(i) Calculate the probability that none of the three selected bulbs is defective.
(ii) Hence, find the probability that at least one of the three selected bulbs is defective.
(iii) Show numerically that the sum of the probabilities obtained in parts (i) and (ii) equals 1.