This is from my teaching materials, can someone explain this to me how does it get vaule of A = 609149 m2????? How do i calculate this.

Total Area A particle with 1m diameter which is charged with 10 electrons is located in an electrical field 50,000V/m (air at 20C and 1atm ). For flow rate of 5000m3/min and an efficiency of 99%, how much area is required? Given data: Flow rate =5000m3/min Drift velocity =0.63mm/s Area of one plate =63=18m2 Efficiency =0.99 Efficiency =ParticleatinletCollectedParticles=InletInletOutlet Efficiency =QC0QC0QCL CL=C0e(QwAP) Rearrangement C0CL=e(QwAP)} 0.99=1e(5000minm360smin0.63smm1000mm1mAm2) A=609149m2 (area of one plate, double side)