Answer:
The volume of air in the auditorium = 5832 cubic meter
Explanation:
Length, breadth, and height of the auditorium = 18m
Therefore, the volume of air in the auditorium

An average adult person requires approximately 0.3 cu.M air per hour.
Therefore:
6480 adult person will require: 0.3 X 6480 = 1944 cu.M air per hour.
For three hours:
6480 adult person will require: = 1944 X 3 =5832 cubic meter of air
We notice that the volume of air in the room will be exhausted exactly after 3 hours when 6480 persons attend.
Therefore, the owner has taken this decision to avoid suffocation as an increase in the number of tickets or hours will cause such.