Red snapper is a rare and expensive reef fish served at upscale restaurants. A certain law prohibits restaurants from serving a​ cheaper, look-alike variety of fish​ (vermilion snapper or lane​ snapper) to customers who order red snapper. Researchers at a university used DNA analysis to examine fish specimens labeled​ "red snapper" that were purchased form vendors across the country. The DNA tests revealed that 78​% of the specimens were not red​ snapper, but the​ cheaper, look-alike variety of fish.

a. Assuming that the results of the DNA analysis are valid, what is the probability that you are actually served red snapper the next time you order it ata restaurant?
b. If there are five customers at a restaurant, all who have ordered red snapper, what is the probability that at least one customer is actually served red snapper?