A box contains seven bulbs out of which 5 are defective. If five bulbs are chosen at random, find the probability that all the five bulbs are defective?	Choices
A) 1/12
B) 1/21
C) 1/19
D) 1/13
E) 1/16
Out of seven, two are good and five are defective. Required probability   = 5C5/7C5   = 1/21   Answer:1/21
<result>B</result>
A box contains seven bulbs out of which 5 are defective. If five bulbs are chosen at random, find the probability that all the five bulbs are defective?