The density of air at ordinary atmospheric pressure and 25 ∘c is 1.19 g/l. what is the mass, in kilograms, of the air in a room that measures 12.5 × 19.5 × 6.0 ft?

Given:
The density of air = 1.19 g/L at 25°C and atmospheric pressure,
or
density = 1.19 x 10⁻³ kg/L

Volume of air in the room is
V = 12.5*19.5*6.0 = 1462.5 ft³

Note that
1 ft³ = 28.317 L
Therefore
V = (1462.5 ft³)*(28.317 L/ft³) = 4.1414 x 10 ⁴ L

By definition, mass = density*volume.
Therefore, the mass is
(1.19 x 10⁻³ kg/L)*(4.1414 x 10⁴ L) = 49.283 kg

49.3 kg (nearest tenth)