price deregulation in the airline industry has promoted competition and a variety of fare structures. prior to deciding on a price change, a particular airline is interested in obtaining an estimate of the proportion of the market that it presently captures for a certain city. a random sample of 300 passengers indicates that 80 used that airline. a) find a point estimate of the proportion of the market that uses this particular airline. b) find a two-sided 95% confidence interval for the proportion that uses this airline. c) can the airline conclude that its market share is more than 25%? use a level of significance of 0.01.