The test suite has been updated to test against a tolerance rather than using isequal.

It's good that the Test Suite was fixed, but the Problem Statement is still inadequate. Liquid water's density varies with temperature, e.g. ~965 kg/m³ at 90 °C, and gravity varies with latitude and elevation, e.g. ~9.78 m/s² at the poles. Density and gravity need to be either specified in the problem statement or else provided as inputs. —DIV

The employed gravity and density values should be part of the problem. Water density changes according to temperature. And according to the gravity's precision, results may vary. It seems that the values used were 9.81 m/s² for gravity and 1029 kg/m³ for water density, which is the maximum value for sea water.