32. Fire load is the heat energy that could be released per square meter of floor area by combustion of contents and the structure itself. The article “Fire Loads in Office Buildings” (J. of Structural Engr., 1997: 365–368) gave the following cumulative percentages (read from a graph)

for fire loads in a sample of 388 rooms:

(MJ/m2)

Value 0 150 300 450 600 Cumulative % 0 19.3 37.6 62.7 77.5 Value 750 900 1050 1200 1350 Cumulative % 87.2 93.8 95.7 98.6 99.1 Value 1500 1650 1800 1950 Cumulative % 99.5 99.6 99.8 100.0

a. Construct a relative frequency histogram and comment on interesting features.

b. What proportion of fire loads are less than 600? At least 1200?

c. What proportion of the loads are between 600 and 1200?