How many person can be accommodated in a dining hall of dimensions 
assuming that each person requires 5 cubic metres of air?
Given,
Dimensions of dining hall = 20m × 16m × 4.5m
Volume of hall = 20 × 16 × 4.5 = 1440 m3
Volume of air required by one person = 5 m3
∴ Number of persons in hall = 
11