A box contains six bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that at least one bulb is good?	Choose the correct choice from the following answers:
A) 21/81 B) 16/81 C) 65/81 D) 2/3 E) 1/2
Required probability   = 1 - 16/81   = 65/81   Answer: 65/81
<result>C</result>
A box contains six bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that at least one bulb is good?