A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random form this box. The probability that at least one of these is defective is:
Choose the correct option:
A) 10/19 B) 7/19 C) 17/19 D) 19/19 E) 14/19
P(none is defective)=16c2/20c2   =12/19   P( at least one is defective)= 1-12/19   =7/19   ANSWER 7/19 7/19
<result>B</result>
A box contains 20 electric bulbs, out of which 4 are defective. Two bulbs are chosen at random form this box. The probability that at least one of these is defective is: