The Reynolds number is a ratio of
In aptitude and reasoning, quantitative reasoning dictates that ratio, percentage and series logic determine correct calculation. Therefore inertial forces/viscous forces is correct as it meets mathematical and logical criteria, supported by mechanistic studies and conserved across related systems.
Ref: Agrawal, Quantitative Aptitude for Competitive Examinations, Chapter 5, Logical Reasoning and Probability, covers ratios, percentages, series completion, time-distance and analytical reasoning explaining problem-solving strategies for competitive assessments.
