Duct Arithmetic: Section Area, Perimeter and Mean Velocity

Duct Arithmetic: Section Area, Perimeter and Mean Velocity

Original quantitative learning practice in English. All 24 questions are included. Four supplied cases exercise six related calculation targets; they form one topic, not four separate tests. Every question includes the complete initial data. Use the stated model and retain intermediate precision. Choose one answer. Learning target: 20/24, not an official pass mark. This bank covers the calculation topic in its title; it is not a complete professional examination, design approval or operating instruction.
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A rectangular section is 0.7 m wide and 0.4 m high. A separate circular section has diameter 0.5 m. The same supplied volume flow 0.8 m³/s passes through either section. Use π=3.1416 and mean velocity=flow/area. This is geometric comparison only; pressure loss, noise and actual duct design are excluded. Calculate the circular area in m². Keep intermediate values unrounded; round the final result to four decimal places if necessary.