[" Determine the probability that the pentaren out hagood one."],[" 9.A lot of "20" bulbs contain "4" defective ones.One bulb is selccted at random from the lot."],[" What is the probability that this bulb is defective? (Suppose the bulb selected in previous "],[" case is not defective and is not replaced.Now one bulb is selected at random from the "],[" rest.What is the probability that this bulb is not defective? "]