A box contains 24 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random from this box. The probability that at least one of these is defective is	Choose the correct choice from the following options: A) 4/19 B) 7/19 C) 12/19 D) 24/77 E) None
Solution   P( None is defective)   = 20C2 / 24C2   = 53/77.   P( at least one is defective)   = (1- 53/77)   = 24/77.   Answer 24/77
<result>D</result>
A box contains 24 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random from this box. The probability that at least one of these is defective is