Suppose that 21% of the subscribers of a cable television company watch the shopping channel at least once a month. The cable company is trying to decide whether to replace this channel with a new local station. A survey of 81 subscribers will be undertaken. The cable company has decided to drop the shopping channel if the sample proportion is less than 0.19. What is the approximate probability that the cable company will drop the shopping channel, even though the true proportion of all subscribers who watch it is 0.21?