Norovirus is a very contagious virus that causes vomiting and diarrhea. People of all ages can get infected and sick with norovirus. Norovirus spreads easily! People with norovirus illness can shed billions of norovirus particles. And only a few virus particles can make other people sick.
Answer: 
Explanation:
If r is the number of successes out of n trials , then the sample proportion of success = 
For binomial experiment , if the population probability of success p on a single trial is not given , then the best point estimate for probability of success p on a single trial is the sample proportion of successes.
i.e. a point estimate for the probability of success p on a single trial :

Hence, a point estimate for the probability of success p on a single trial = 
Answer:
D. is imperfectly competitive, but not all imperfectly competitive markets are monopolistically competitive.
Explanation:
Monopolistic competition may be seen as a variety of competition that determine the characteristics of variety of industries that are familiar to consumers in their day-to-day lives. For instance, restaurants, hair salons, clothing, and consumer electronics are all monopolistic competitive market but not all imperfectly competitive markets are monopolistically competitive.