A box contains 23 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 Select
A) 4/19  B) 7/19  C) 12/37  D) 21/95  E) None
Solution   P( None is defective)   = 19C2 / 23C2   = 25/37.   P( at least one is defective)   = (1- 25/37)   = 12/37.   Answer 12/37
<result>C</result>
A box contains 23 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