Suppose that currently 80% of the population aged 12 or older in Puerto Rico have been fully vaccinated against Covid-19. For a random sample of 100 people aged 12 or older in Puerto Rico, let p denote the sample proportion of who have been fully vaccinated against Covid-19. a) (7 pts) Find the mean and standard deviation of the sampling distribution of the sample proportion p._ b) (7 pts) Explain why it is almost certain that the sample proportion p will fall within 0.68 and 0.92. c) (7 pts) Find the probability that between 75% and 85% of the people in the random sample have been fully vaccinated against Covid-19 (that is, find the probability that p falls within 0.75 and 0.85)