Calculating mass without inventing firmness

A job worksheet specifies a rectangular foam slab 1.80 m long, 0.50 m wide and 0.12 m thick, with supplied density 40 kg per cubic metre. A trainee calculates its volume and mass, then declares that the result also proves exactly how firm the cushion will feel. The supervisor distinguishes the mathematical mass estimate from independently measured compression behaviour, recovery and the response of the complete suspension and covering assembly. The dimensions and density are hypothetical supplied parameters, not official CAP requirements or universal supplier tolerances. The calculation excludes wadding, adhesive, cover fabric and any added edge profile. Before ordering, actual product data and the agreed use would still be checked. The exercise concerns dimensional reasoning and the distinction between two material properties.