What type of consumers of a live concert might purchase tickets to a concert early? Why might the promoter of the concert choose to have advanced ticket sales? In what ways do these advanced ticket sales enable a scalper to make a profit? Under what conditions is the scalper performing a useful economic purpose? Describe a situation in which the scalper could disrupt the efficient allocation of tickets, when there is advanced ticket sales? How could this be prevented, or at least mitigated?